Abstract: Ideomotor theories of human action control assume that performing a movement leads to the automatic integration of the underlying motor pattern with codes of its perceptual consequences. We studied the microgenesis of action-effect integration by varying the mapping of action effects upon actions from trial to trial. Experiments 1 and 2 showed that perceiving a tone repetition systematically affects one's tendency to carry out the response that produced that tone in the previous trial, suggesting that even the unintentional production of a stimulus creates a temporary binding of that stimulus with the action that brought it about. Experiments 3 and 4 extended this finding in suggesting that the integration and/or retrieval of action effects is modulated by attentional factors: Ongoing performance is more impacted by action effects if they are salient or match the current attentional set.
Abstract: Perceiving an event requires the integration of its features across numerous brain maps and modules. Visual object perception is thought to be mediated by a ventral processing stream running from occipital to inferotemporal cortex, whereas most spatial processing and action control is attributed to the dorsal stream connecting occipital, parietal, and frontal cortex. Here we show that integration operates not only on ventral features and objects, such as faces and houses, but also across ventral and dorsal pathways, binding faces and houses to motion and manual action. Furthermore, these bindings seem to persist over time, as they influenced performance on future task-relevant visual stimuli. This is reflected by longer reaction times for repeating one, but alternating other features in a sequence, compared to complete repetition or alternation of features. Our findings are inconsistent with the notion that the dorsal stream is operating exclusively online and has no access to memory.
Abstract: The present fMRI study sought to investigate the neural basis of perceiving learned action effects and thereby to test for hypotheses based on the ideomotor principle. For this purpose, we had subjects undergo a two-phase experimental procedure comprising an acquisition and a test phase, the latter administered inside the MR scanner. During the acquisition phase, free-choice button presses were contingently followed by one of two tones of different pitch which thereby should become "learned action effects". During the following test phase, subjects were presented with the action effects either when in a passive (non-acting) state or when they carried out forced-choice button presses. Conform to our expectations, we found evidence for a motor effector activation following the passive perception of effect tones which elicited activation in the neural motor system (premotor and somatosensory cortices, SMA, and cerebellum). Surprisingly, however, this activation was observed for left-hand effect tones only, suggesting a basic asymmetry in the impact of ideomotor learning. Moreover, we found activation in the posterior prefrontal and temporo-parietal cortex in response to action effects during the pursuit of goal-directed action. This suggests that action effects attracted special attention and thereby engaged selective cognitive control processes to ensure task-appropriate performance. Finally, there was reduced premotor activation for response-compatible as compared to response-incompatible action effects which can be taken as indication for differential requirements on the motor system and thus for behavioral interference and/or facilitation by learned action effects.
Abstract: The primate cortex represents and produces events in a distributed way, which calls for a mechanism that integrates their features into coherent structures. Visuomotor integration seems to be driven by dopaminergic (DA) pathways but which subsystems are involved is currently unknown. The present study compared the impact of the recreational use of two drugs on visuomotor integration: cannabis, which primarily targets dopaminergic D1 receptors, and cocaine, which mainly targets D2 receptors. Our findings show that cannabis but not cocaine use affects the strength of the binding between task-relevant stimulus features and the accompanying response. In contrast, cocaine but not cannabis use eliminates the inhibition of return. The observed pattern suggests that visuomotor integration is driven by DA/D1, but not DA/D2 receptor systems.
Abstract: The primate cortex represents perceived and produced events in a distributed way, which calls for a mechanism that integrates their features into coherent structures. Animal, drug, and patient studies suggest that the local binding of visual features is under muscarinic-cholinergic control, whereas visuomotor binding seems to be driven by dopaminergic pathways. Consistent with this picture, we present evidence that the binding of visual features and actions is modulated by stress, induced by the cold pressure test (CPT), which causes an excessive dopamine turnover in prefrontal cortex. The impact of stress was restricted to the task-relevant visuomotor binding, supporting claims that dopamine affects the maintenance of task-relevant information in working memory. The outcome pattern, including the impact of the personality trait extraversion, suggests that the relation between dopamine level and visuomotor performance follows an inverted U-shaped function, with strongest binding being associated with average dopamine levels.
Abstract: The Attentional Blink (AB) - a deficit in reporting the second of two target stimuli presented in close succession in a rapid sequence of distracters - has been related to individual processing limitations of working memory. Given the known role of dopamine (DA) in working memory processes, the present experiment tested the hypothesis that DA, and in particular the DA/D1 subsystem, plays a role in the AB. We present evidence that the spontaneous eyeblink rate (EBR), a functional marker of central dopaminergic function, reliably predicts the size of AB. Thus, in line with our hypothesis, these data point to a modulatory role for DA in the AB.
Abstract: Identifying 2 target stimuli in a rapid stream of visual symbols is much easier if the 2nd target appears immediately after the 1st target (i.e., at Lag 1) than if distractor stimuli intervene. As this phenomenon comes with a strong tendency to confuse the order of the targets, it seems to be due to the integration of both targets into the same attentional episode or object file. The authors investigated the degree to which people can control the temporal extension of their (episodic) integration windows by manipulating the expectations participants had with regard to the time available for target processing. As predicted, expecting more time to process increased the number of order confusions at Lag 1. This was true for between-subjects and within-subjects (trial-to-trial) manipulations, suggesting that integration windows can be adapted actively and rather quickly.
Abstract: It has been claimed that bilingualism enhances inhibitory control, but the available evidence is equivocal. The authors evaluated several possible versions of the inhibition hypothesis by comparing monolinguals and bilinguals with regard to stop signal performance, inhibition of return, and the attentional blink. These three phenomena, it can be argued, tap into different aspects of inhibition. Monolinguals and bilinguals did not differ in stop signal reaction time and thus were comparable in terms of active-inhibitory efficiency. However, bilinguals showed no facilitation from spatial cues, showed a strong inhibition of return effect, and exhibited a more pronounced attentional blink. These results suggest that bilinguals do not differ from monolinguals in terms of active inhibition but have acquired a better ability to maintain action goals and to use them to bias goal-related information. Under some circumstances, this ability may indirectly lead to more pronounced reactive inhibition of irrelevant information.
Abstract: The age-correlated gains and losses in visual identification under backward pattern masking were studied in a representative sample of 226 individuals ranging from 6 to 88 years of age. Participants identified masked symbols at leisure under high and low stimulus quality and at varying Stimulus Onset Asynchronies. Performance increased from childhood to early adulthood and then decreased, describing the common inverted U-shaped function. However, measures of general processing speed accounted for the gains in childhood and adolescence but not for losses in older age. This asymmetry between child development and aging is inconsistent with general-factor lifespan theories of cognitive development and suggests that specific mechanisms underlying visual identification during child development and aging are different.
Abstract: The authors argue that human sequential learning is often but not always characterized by a shift from stimulus- to plan-based action control. To diagnose this shift, they manipulated the frequency of 1st-order transitions in a repeated manual left-right sequence, assuming that performance is sensitive to frequency-induced biases under stimulus- but not plan-based control. Indeed, frequency biases tended to disappear with practice, but only for explicit learners. This tendency was facilitated by visual-verbal target stimuli, response-contingent sounds, and intentional instructions and hampered by auditory (but not visual) noise. Findings are interpreted within an event-coding model of action control, which holds that plans for sequences of discrete actions are coded phonetically, integrating order and relative timing. The model distinguishes between plan acquisition, linked to explicit knowledge, and plan execution, linked to the action control mode.
Abstract: The primate cortex represents the external world in a distributed fashion, which calls for a mechanism that integrates and binds the features of a perceived or processed event. Animal and patients studies provide evidence that feature binding in the visual cortex is driven by the muscarinic-cholinergic system, whereas visuo-motor integration may be under dopaminergic control. Consistent with this scenario, we present indication that the binding of visual and action features is modulated by emotions through the probable stimulation of the dopaminergic system. Interestingly, the impact of emotions on binding was restricted to tasks in which shape was task-relevant, suggesting that extracting affective information is not automatic but requires attention to shape.
Abstract: We investigated whether it is possible to control the temporal window of attention used to rapidly integrate visual information. To study the underlying neural mechanisms, we recorded ERPs in an attentional blink task, known to elicit Lag-1 sparing. Lag-1 sparing fosters joint integration of the two targets, evidenced by increased order errors. Short versus long integration windows were induced by showing participants mostly fast or slow stimuli. Participants expecting slow speed used a longer integration window, increasing joint integration. Difference waves showed an early (200 ms post-T2) negative and a late positive modulation (390 ms) in the fast group, but not in the slow group. The modulations suggest the creation of a separate event for T2, which is not needed in the slow group, where targets were often jointly integrated. This suggests that attention can be guided by global expectations of presentation speed within tens of milliseconds.
Abstract: Five experiments investigated the spontaneous integration of stimulus and response features. Participants performed simple, prepared responses (R1) to the mere presence of Go signals (S1) before carrying out another, freely chosen response (R2) to another stimulus (S2), the main question being whether the likelihood of repeating a response depends on whether or not the stimulus, or some of its features, are repeated. Indeed, participants were more likely to repeat the previous response if stimulus form or color was repeated than if it was alternated. The same was true for stimulus location, but only if location was made task-relevant, whether by defining the response set in terms of location, by requiring the report of S2 location, or by having S1 to be selected against a distractor. These findings suggest that task-relevant stimulus and response features are spontaneously integrated into independent, local event files, each linking one stimulus to one response feature. Upon reactivation of one member of the binary link activation is spread to the other, thereby increasing the likelihood to repeat a response if one or more stimulus features are repeated. These findings support the idea that both perceptual events and action plans are cognitively represented in terms of their features, and that feature-integration processes cross borders between perception and action.
Abstract: Neurophysiological observations suggest that attending to a particular perceptual dimension, such as location or shape, engages dimension-related action, such as reaching and prehension networks. Here we reversed the perspective and hypothesized that activating action systems may prime the processing of stimuli defined on perceptual dimensions related to these actions. Subjects prepared for a reaching or grasping action and, before carrying it out, were presented with location- or size-defined stimulus events. As predicted, performance on the stimulus event varied with action preparation: planning a reaching action facilitated detecting deviants in location sequences whereas planning a grasping action facilitated detecting deviants in size sequences. These findings support the theory of event coding, which claims that perceptual codes and action plans share a common representational medium, which presumably involves the human premotor cortex.
Abstract: Theories of selective attention often have a central memory component, which is commonly thought to be limited in some way and is thereby a potential bottleneck in the attentional process. There have been only a few attempts to validate this assertion, and they have produced mixed results. This study presents a specific examination of the link between working memory and attention by engaging active rather than passive memory operations. Two experiments are reported that provide evidence for the involvement of working memory in the attentional blink (AB) phenomenon. Memory loads of increasing size had a detrimental effect on attentional performance within the blink-sensitive interval, but not beyond. Speeded response requirements proved to modulate the AB, but were independent from the memory load effect. Theoretical implications for current models of selective attention are discussed.
Abstract: Chronic use of cocaine is associated with impairment in response inhibition but it is an open question whether and to which degree findings from chronic users generalize to the upcoming type of recreational users. This study compared the ability to inhibit and execute behavioral responses in adult recreational users and in a cocaine-free-matched sample controlled for age, race, gender distribution, level of intelligence, and alcohol consumption. Response inhibition and response execution were measured by a stop-signal paradigm. Results show that users and non users are comparable in terms of response execution but users need significantly more time to inhibit responses to stop-signals than non users. Interestingly, the magnitude of the inhibitory deficit was positively correlated with the individuals lifetime cocaine exposure suggesting that the magnitude of the impairment is proportional to the degree of cocaine consumed.
Abstract: Two experiments investigated the capacity demands of stimulus and response priming in a rapid serial visual presentation (RSVP) task. Three targets were presented in a stream of visual symbols: The first two (T1 and T2) required an unspeeded manual response at the end of the trial, but the third (T3) called for an immediate,speeded manual response. T2 and T3 either were identical (fully compatible), required the same response (response compatible), or required different responses (incompatible). Priming in the fully compatible condition depended strongly on successful identification of the priming stimulus, whereas response-based priming was observed regardless of whether the prime could be reported or not. These findings suggest that stimulus coding and response coding are automatic processes, unaffected by attentional capacity constraints, followed by capacity-limited stimulus consolidation and response selection. Moreover, even though response codes are activated automatically upon stimulus processing, both types of codes act, and affect behavior, independently.
Abstract: The attentional blink (AB) is often attributed to resource limitations, but the nature of these resources is commonly underspecified. Recent observations rule out access to short-term memory or storage capacity as limiting factors, but operation bottlenecks are still an option. We considered the operation span of working memory (WM) as a possible factor and investigated the relationship between individual WM operation span (as measured by OSPAN), fluid intelligence (as measures by Raven's SPM), and the size of the AB. WM operation span was negatively correlated with the AB, whereas fluid intelligence was associated with higher overall accuracy but not with AB magnitude. These results support the idea that individual processing limitations (with regard to either attentional allocation policies or the speed of global cortical integration processes) play a key role in the AB.
Abstract: The primate cortex represents the external world in a distributed way, which requires for a mechanism that integrates the features of a processed event. Animal and patients studies suggest that feature binding in the visual cortex is under muscarinic-cholinergic control, whereas visuomotor integration is driven by the dopaminergic system. Consistent with this picture, we present evidence that the binding of visual and action features is modulated by spontaneous eyeblink rate (EBR), which is a functional marker of central dopaminergic function. Remarkably, the impact of EBR was restricted to the task-relevant visuomotor binding, suggesting that dopamine increased the maintenance of task-relevant information.
Abstract: Two lines of research on cross-task priming yield opposite results. Research on repetition priming observed positive priming, whereas research on the role of priming in task-switching observed negative effects. We combined the two types of design. In the transfer phase of our paradigm, subjects performed task B either as a pure block (BBB) or as a switch block (ABAB). We presented items which were either unprimed or primed by prior presentation during a preceding priming phase performed on task A. Amongst others, the priming effect is determined by two factors: First, the more operation time the system needs during the probe event, the higher the likelihood to obtain priming. Protracting operation time by reducing stimulus quality favors positive priming, whereas providing more operation time by making subjects switch between tasks favors negative priming. Second, the strength of the memory trace of the prime event determines whether that trace can possibly yield negative priming, in that only strong traces can be retrieved together with the associated task/response.
Abstract: Previous findings suggest that planning an action "backward-primes" perceptual dimension related to this action: planning a grasp facilitates the processing of visual size information, while planning a reach facilitates the processing of location information. Here we show that dimensional priming of perception through action occurs even in the absence of active action planning. Subjects watched video clips showing a grasping or reaching action before detecting size- or location-defined deviants in visual stimulus sequences. Size deviants were detected faster after seeing a grasp and location deviants were detected faster after seeing a reach. This supports the assumption that perceptual codes and action plans share a common representational medium, and that "attention to action" controls "attention to stimuli".
Abstract: Humans have difficulty processing more than one event at a time, as is evidenced by the attentional blink ('blink') phenomenon: the second of two targets in a visual stream of events cannot be reported accurately if it appears between 100 and 500 ms after the first. By using whole-head magnetoencephalography, we show that the probability of behaviourally failing to correctly identify the second target can be predicted from the amount of attentional resources devoted to processing the first target, as indexed by T1 activation. This important finding supports resource sharing accounts of divided attention tasks such as the 'blink'; that is, such tasks may reflect an individual processing strategy rather than an immutable structural processing bottleneck.
Abstract: Previous studies showed that the identification of a left- or right-pointing arrowhead is impaired when it appears while planning and executing a spatially compatible left or right keypress (Müsseler & Hommel, 1997a). We attribute this effect to stimulus processing and action control operating on the same feature codes so that, once a code is integrated in an action plan, it is less available for perceptual processing. In three pairs of experiments we tested the generality of this account by using stimulus-response combinations other than arrows and manual keypresses. Planning manual left-right keypressing actions impaired the identification of spatially corresponding arrows but not of words with congruent meaning. On the contrary, planning to say "left" or "right" impaired the identification of corresponding spatial words but not of congruent arrows. Thus, as the feature-integration approach suggests, stimulus identification is impaired only with overlap of perceptual or perceptually derived stimulus and response features while mere semantic congruence is insufficient.
Abstract: Explicit and implicit learning have been attributed to different learning processes that create different types of knowledge structures. Consistent with that claim, our study provides evidence that people integrate stimulus events differently when consciously aware versus unaware of the relationship between the events. In a first, acquisition phase participants sorted words into two categories (A and B), which were fully predicted by task-irrelevant primes-the labels of two other, semantically unrelated categories (C and D). In a second, test phase participants performed a lexical decision task, in which all word stimuli stemmed from the previous prime categories (C and D) and the (now nonpredictive) primes were the labels of the previous target categories (A and B). Reliable priming effects in the second phase demonstrated that bidirectional associations between the respective categories had been formed in the acquisition phase (A<-->C and B<-->D), but these effects were found only in participants that were unaware of the relationship between the categories! We suggest that unconscious, implicit learning of event relationships results in the rather unsophisticated integration (i.e., bidirectional association) of the underlying event representations, whereas explicit learning takes the meaning of the order of the events into account, and thus creates unidirectional associations.
Abstract: When people monitor a visual stream of rapidly presented stimuli for two targets (T1 and T2), they often miss T2 if it falls into a time window of about half a second after T1 onset-the attentional blink (AB). We provide an overview of recent neuroscientific studies devoted to analyze the neural processes underlying the AB and their temporal dynamics. The available evidence points to an attentional network involving temporal, right-parietal and frontal cortex, and suggests that the components of this neural network interact by means of synchronization and stimulus-induced desynchronization in the beta frequency range. We set up a neurocognitive scenario describing how the AB might emerge and why it depends on the presence of masks and the other event(s) the targets are embedded in. The scenario supports the idea that the AB arises from "biased competition", with the top-down bias being generated by parietal-frontal interactions and the competition taking place between stimulus codes in temporal cortex.
Abstract: Everyday human behaviour relies on our ability to predict outcomes on the basis of moment by moment information. Long-range neural phase synchronization has been hypothesized as a mechanism by which 'predictions' can exert an effect on the processing of incoming sensory events. Using magnetoencephalography (MEG) we have studied the relationship between the modulation of phase synchronization in a cerebral network of areas involved in visual target processing and the predictability of target occurrence. Our results reveal a striking increase in the modulation of phase synchronization associated with an increased probability of target occurrence. These observations are consistent with the hypothesis that long-range phase synchronization plays a critical functional role in humans' ability to effectively employ predictive heuristics.
Abstract: Four experiments were conducted to investigate the relationship between the binding of visual features (as measured by their aftereffects on subsequent binding) and the learning of feature-conjunction probabilities. Both binding and learning effects were obtained, but they did not interact. Interestingly, (shape-color) binding effects disappeared with increasing practice, presumably because of the fact that only 1 of the features involved was relevant to the task. However, this instability was only observed for arbitrary, not highly overlearned combinations of simple geometric features and not for real objects (colored pictures of a banana and strawberry), where binding effects were strong and resistant to practice. These findings suggest that learning has no direct impact on the strength or resistance of bindings or on speed with which features are bound; however, learning does affect the amount of attention particular feature dimensions attract, which again can influence which features are considered in binding.
Abstract: People integrate the features of perceived events and of action plans, as well as of episodic stimulus-response relations, into event files. We investigated whether the management of event files, and particularly the speed of updating the binding between the task-relevant stimulus feature and the response, correlates with fluid intelligence. Indeed, the performance of participants scoring high on Raven's Standard Progressive Matrices test was less impaired by a mismatch between the stimulus-response relation in the current and the previous trial. This result suggests that high intelligence is accompanied by a higher degree of flexibility in handling event files--that is, by higher efficiency in updating episodic representations.
Abstract: Individual performance was compared across three different tasks that tap into the binding of stimulus features in perception, the binding of action features in action planning, and the emergence of stimulus-response bindings ("event files"). Within a task correlations between the size of binding effects were found within visual perception (e.g., the strength of shape-location binding correlated positively with the strength of shape-colour binding) but not between perception and action planning, suggesting different, domain-specific binding mechanisms. To some degree, binding strength was predicted by priming effects of the respective features, especially if these features varied on a dimension that matched the current attentional set.
Abstract: This study examined the role of verbal labeling in 4-year-old children's acquisition of action-effect learning. The acquisition of action-effect associations was tested by having children first perform a two-choice key-pressing task in which each key press was followed by an effect (i.e., a particular sound) and then respond to the previously perceived effects under either consistent or inconsistent key-sound mappings. During acquisition, the children overtly described the actions, the effects, both the actions and the effects, or, in a control condition, something irrelevant to the actions and effects. Action-effect learning was reliable only if the description related actions to effects, even though some evidence of learning was also obtained in the control condition. In contrast, learning was prevented if only the actions or only the effects were described. The results suggest that verbal labeling plays an important role in integrating and isolating event representations.
Abstract: If humans monitor streams of rapidly presented (approximately 100-ms intervals) visual stimuli, which are typically specific single letters of the alphabet, for two targets (T1 and T2), they often miss T2 if it follows T1 within an interval of 200-500 ms. If T2 follows T1 directly (within 100 ms; described as occurring at 'Lag 1'), however, performance is often excellent: the so-called 'Lag-1 sparing' phenomenon. Lag-1 sparing might result from the integration of the two targets into the same 'event representation', which fits with the observation that sparing is often accompanied by a loss of T1-T2 order information. Alternatively, this might point to competition between the two targets (implying a trade-off between performance on T1 and T2) and Lag-1 sparing might solely emerge from conditional data analysis (i.e. T2 performance given T1 correct). We investigated the neural correlates of Lag-1 sparing by carrying out magnetoencephalography (MEG) recordings during an attentional blink (AB) task, by presenting two targets with a temporal lag of either 1 or 2 and, in the case of Lag 2, with a nontarget or a blank intervening between T1 and T2. In contrast to Lag 2, where two distinct neural responses were observed, at Lag 1 the two targets produced one common neural response in the left temporo-parieto-frontal (TPF) area but not in the right TPF or prefrontal areas. We discuss the implications of this result with respect to competition and integration hypotheses, and with respect to the different functional roles of the cortical areas considered. We suggest that more than one target can be identified in parallel in left TPF, at least in the absence of intervening nontarget information (i.e. masks), yet identified targets are processed and consolidated as two separate events by other cortical areas (right TPF and PFC, respectively).
Abstract: The distributed organization of the human visual cortex calls for a mechanism that integrates and binds the features of a perceived event, and neural synchronization is a prime candidate to serve that purpose. Animal studies suggest that synchronization in the visual cortex is enhanced by the muscarinic cholinergic system. Here we show that in healthy humans the binding of shape and colour, and of shape and location, of visual objects is increased by stimulating the muscarinic cholinergic system (caffeine consumption) but not by stimulating the nicotinic cholinergic system (nicotine consumption). Binding across perception and action is unaffected by either manipulation, suggesting a specific link between the visual system and the muscarinic cholinergic system.
Abstract: Response selection bottleneck models attribute performance costs under dual-task conditions to the human inability to select more than one response at a time. Consistent with this claim Pashler (1991) found that carrying out a speeded manual choice reaction time (RT) task does not impair the unspeeded report of a cued visual target from a masked display. In contrast, Jolicoeur and Dell'Acqua (1999, Experiment 2) observed pronounced interference between a speeded manual choice RT task and the unspeeded report of a small number of visually presented letters, a finding they attributed to resource sharing between response selection and stimulus consolidation. We demonstrate that comparable costs are obtained with the same task combination used by Pashler (1991) if only task order is reversed-a manipulation that is likely to increase the necessity of consolidating the target stimulus into working memory. We also found that these costs are not diminished if the location of the target to be reported is cued in advance (reducing demands on spatial focusing) and that they do not vary with the number of target features to be reported. These findings support a consolidation account of costs in dual-task performance.
Abstract: When people monitor a visual stream of rapidly presented stimuli for two targets (T1 and T2), they often miss T2 if it falls into a time window of about half a second after T1 onset--the attentional blink. However, if T2 immediately follows T1, performance is often reported being as good as that at long lags--the so-called Lag-1 sparing effect. Two experiments investigated the mechanisms underlying this effect. Experiment 1 showed that, at Lag 1, requiring subjects to correctly report both identity and temporal order of targets produces relatively good performance on T2 but relatively bad performance on T1. Experiment 2 confirmed that subjects often confuse target order at short lags, especially if the two targets are equally easy to discriminate. Results suggest that, if two targets appear in close succession, they compete for attentional resources. If the two competitors are of unequal strength the stronger one is more likely to win and be reported at the expense of the other. If the two are equally strong, however, they will often be integrated into the same attentional episode and thus get both access to attentional resources. But this comes with a cost, as it eliminates information about the targets' temporal order.
Abstract: We investigated the nature of resource limitations during visual target processing by imposing high temporal processing demands on the cognitive system. This was achieved by embedding target stimuli into rapid-serial-visual-presentation-streams (RSVP). In RSVP streams, it is difficult to report the second of two targets (T2) if the second follows the first (T1) within 500 ms. This effect is known as the attentional blink (AB). For the AB to occur, it is essential that T1 is followed by a mask, as without such a stimulus, the AB is significantly attenuated. Usually, it is thought that T1 processing is delayed by the mask, which in turn delays T2 processing, increasing the likelihood for T2 failures (AB). Predictions regarding amplitudes and latencies of cortical responses (M300, the magnetic counterpart to the P300) to targets were tested by investigating the neurophysiological effects of the post-T1 item (mask) by means of magnetoencephalography (MEG). Cortical M300 responses to targets drawn from prefrontal sources--areas associated with working memory--revealed accelerated T1 yet delayed T2 processing with an intervening mask. The explanation we are proposing assumes that "protection" of ongoing T1 processing necessitated by the occurrence of the mask suppresses other activation patterns, which boosts T1 yet also hinders further processing. Our data shed light on the mechanisms employed by the human brain for ensuring visual target processing under high temporal processing demands, which is hypothesized to occur at the expense of subsequently presented information.
Abstract: If people monitor a visual stimulus stream for targets they often miss the second (T2) if it appears soon after the first (T1)--the attentional blink. There is one exception: T2 is often not missed if it appears right after T1, i.e., at lag 1. This lag-1 sparing is commonly attributed to the possibility that T1 processing opens an attentional gate, which may be so sluggish that an early T2 can slip in before it closes. We investigated why the gate may close and exclude further stimuli from processing. We compared a control approach, which assumes that gate closing is exogenously triggered by the appearance of nontargets, and an integration approach, which assumes that gate closing is under endogenous control. As predicted by the latter but not the former, T2 performance and target reversals were strongly affected by the temporal distance between T1 and T2, whereas the presence or the absence of a nontarget intervening between T1 and T2 had little impact.
Abstract: According to EC regulations the deliberate release of genetically modified (GM) crops into the agro-environment needs to be accompanied by environmental monitoring to detect potential adverse effects, e.g. unacceptable levels of gene flow from GM to non-GM crops, or adverse effects on single species or species groups thus reducing biodiversity. There is, however, considerable scientific and public debate on how GM crops should be monitored with sufficient accuracy, discussing questions of potential adverse effects, agro-environmental variables or indicators to be monitored and respective detection methods; Another basic component, the appropriate number and location of monitoring sites, is hardly considered. Currently, no consistent GM crop monitoring approach combines these components systematically. This study focuses on and integrates spatial agro-environmental aspects at a landscape level in order to design monitoring networks. Based on examples of environmental variables associated with the cropping of Bt-Maize (Zea maize L.), herbicide-tolerant (HT) winter oilseed rape (Brassica napus L.), HT sugar beet (Beta vulgaris L.), and starch-modified potato (Solanum tuberosum L.), we develop a transferable framework and assessment scheme that comprises anticipated adverse environmental effects, variables to be measured and monitoring methods.These we integrate with a rule-based GIS (geographic information system) analysis, applying widely available spatial area and point information from existing environmental networks. This is used to develop scenarios with optimised regional GM crop monitoring networks.
Abstract: When people monitor the rapid serial visual presentation (RSVP) of stimuli for two targets (T1 and T2), they often miss T2 if it falls into a time window of about half a second after T1 onset, a phenomenon known as the attentional blink (AB). We found that overall performance in an RSVP task was impaired by a concurrent short-term memory (STM) task and, furthermore, that this effect increased when STM load was higher and when its content was more task relevant. Loading visually defined stimuli and adding articulatory suppression further impaired performance on the RSVP task, but the size of the AB over time (i.e., T1-T2 lag) remained unaffected by load or content. This suggested that at least part of the performance in an RSVP task reflects interference between competing codes within STM, as interference models have held, whereas the AB proper reflects capacity limitations in the transfer to STM, as consolidation models have claimed.
Abstract: Attentional requirements for the spontaneous integration of stimulus and response features were analyzed. In line with previous findings, carrying out a prepared response to the onset of a stimulus created bindings between the response and the features of that stimulus, thereby impairing subsequent performance on mismatching stimulus-response combinations. Findings demonstrate that a stimulus gets bound to a response even if its presence is neither necessary nor useful for the task at hand, it follows rather than precedes the response in time, it competes with a task-relevant stimulus, and if the response is suppressed--but only if the stimulus appears close to the response's eventual execution or abandonment. A multiple-integration model is suggested that assumes that the integration of stimulus features in perception and of response features in action planning are local processes that are independent of stimulus-response integration, which presumably is triggered by the success of the perception-action episode.
Abstract: When subjects switch between tasks, performance is slower after a task switch than after a task repetition, even when preparation time is long. We report two experiments that support the idea that a large part of these residual task shift costs can be due to stimulus-cued retrieval of previous task episodes. We demonstrate that there are two different factors at work: (1) facilitation of response to the current distractor stimulus, appropriate to the previously relevant, competing task (competitor priming), and (2) impaired processing of previously suppressed responses (negative priming). Negative priming was contingent on the size of the stimulus set, suggesting that distractor suppression comes into effect only if the distractors are highly activated. Importantly, both types of interference interacted with task readiness: Whereas in the nondominant task (picture naming), switch and nonswitch trials were equally affected, the dominant task (word reading) showed priming effects on switch trials only. Thus, the retrieval of previous processing episodes has a selective impact on situations in which task competition is high.
Abstract: Recent studies have shown that the effects of irrelevant spatial stimulus-response (S-R) correspondence (i.e., the Simon effect) occur only after trials in which the stimulus and response locations corresponded. This has been attributed to the gating of irrelevant information or the suppression of an automatic S-R route after experiencing a noncorresponding trial-a challenge to the widespread assumption of direct, intentionally unmediated links between spatial stimulus and response codes. However, trial sequences in a Simon task are likely to produce effects of stimulus- and response-feature integration that may mimic the sequential dependencies of Simon effects. Four experiments confirmed that Simon effects are eliminated if the preceding trial involved a noncorresponding S-R pair. However, this was true even when the preceding response did not depend on the preceding stimulus or if the preceding trial required no response at all. These findings rule out gating/suppression accounts that attribute sequential dependencies to response selection difficulties. Moreover, they are consistent with a feature-integration approach and demonstrate that accounting for the sequential dependencies of Simon effects does not require the assumption of information gating or response suppression.
Abstract: According to the two-stage model of voluntary action, the ability to perform voluntary action is acquired in two sequential steps. Firstly, associations are acquired between representations of movements and of the effects that frequently follow them. Secondly, the anticipation or perception of an acquired action effect primes the movement that has been learnt to produce this effect; the acquired action-effect associations thus mediate the selection of actions that are most appropriate to achieve an intended action goal. If action-effect learning has an associative basis, it should be influenced by factors that are known to affect instrumental learning, such as the temporal contiguity and the probabilistic contingency of movement and effect. In two experiments, the contiguity or the contingency between key presses and subsequent tones was manipulated in various ways. As expected, both factors affected the acquisition of action-effect relations as assessed by the potency of action effects to prime the corresponding action in a later behavioral test. In particular, evidence of action-effect associations was obtained only if the effect of the action was delayed for no more than 1 s, if the effect appeared more often in the presence than in the absence of the action, or if action and effect were entirely uncorrelated but the effect appeared very often. These findings support the assumption that the control of voluntary actions is based on action-effect representations that are acquired by associative learning mechanisms.
Abstract: Two-component theories of intellectual development over the life span postulate that fluid abilities develop earlier during child development and decline earlier during aging than crystallized abilities do, and that fluid abilities support or constrain the acquisition and expression of crystallized abilities. Thus, maturation and senescence compress the structure of intelligence by imposing age-specific constraints upon its constituent processes. Hence, the couplings among different intellectual abilities and cognitive processes are expected to be strong in childhood and old age. Findings from a population-based study of 291 individuals aged 6 to 89 years support these predictions. Furthermore, processing robustness, a frequently overlooked aspect of processing, predicted fluid intelligence beyond processing speed in old age but not in childhood, suggesting that the causes of more compressed functional organization of intelligence differ between maturation and senescence. Research on developmental changes in functional brain circuitry may profit from explicitly recognizing transformations in the organization of intellectual abilities and their underlying cognitive processes across the life span.
Abstract: The implications of an ideomotor approach to action control were investigated. In Experiment 1, participants made manual responses to letter stimuli and they were presented with response-contingent color patches, i.e., colored action effects. This rendered stimuli of the same color as an action's effect effective primes of that action, suggesting that bilateral associations were created between actions and the effects they produced. Experiment 2 combined this set-up with a manual Stroop task, i.e., participants responded to congruent, neutral, or incongruent color-word compounds. Standard Stroop effects were observed in a control group without action effects and in a group with target-incompatible action effects, but the reaction time Stroop effect was eliminated if actions produced target-compatible color effects (e.g., blue word --> left key --> blue patch). Experiment 3 did not replicate this interaction between target-effect compatibility and color-word congruency with color words as action effects, which rules out semantically based accounts. Theoretical implications for both action-effect acquisition and the Stroop effect are discussed. It is suggested that learning action effects, the features of which overlap with the target, allows and motivates people to recode their actions in ways that make them more stimulus-compatible. This provides a processing shortcut for translating the relevant stimulus into the correct response and, thus, shields processing from the impact of competing word distractors.
Abstract: Voluntary action is anticipatory and, hence, must depend on associations between actions and their perceivable effects. We studied the acquisition of action-effect associations in 4-5-vs. 7-year-old children. Children carried out key-pressing actions that were arranged to produce particular auditory effects. In a subsequent test phase, children were to press keys in response to the previous effect sounds, with the sound-key mapping being either consistent or inconsistent with previous key-sound practice. As the processes underlying voluntary action controls are known to significantly improve between 4 and 7 years of age, it was expected that younger children were more prone to automatic effects of acquired sound-key associations. This hypothesis was confirmed, but reaction times and accuracy measures showed different and dissociable patterns. Four-year-olds but not 7-year-olds were more likely to commit an error--i.e., to perform a sound-compatible rather than the correct action--if the sound-key mapping was inconsistent with previous practice. This effect strongly depended on previous practice, suggesting that it reflects long-term learning. In contrast, reaction time effects of mapping consistency did not depend on previous experience but only on the consistency between stimulus and action effect in the present task. Taken altogether, the results suggest that children acquire response-effect associations automatically and that younger children are more likely to suffer from frequent goal neglect; i.e., they tend to forget the current action goal, so that their behavior is dominated by automatic, stimulus-triggered response tendencies.
Abstract: People find it difficult to switch between two tasks, even if they have time to prepare-the so-called residual task shift cost. We studied a switch of tasks from picture naming to word reading, using picture-word Stroop stimuli. Consistent with previous findings, we demonstrate that a large part of the observed task shift cost was due to priming from prior stimulus-response episodes, in which the current task stimulus was encountered in a competing task. We further show that this task-priming effect generalizes to semantically related stimuli, which opens the possibility that most or all of these residual shift costs reflect some sort of generalized proactive interference from previous stimulus-task episodes.
Abstract: Animal studies suggest a relationship between activation of the cholinergic system and neural synchronization, which again has been suggested to mediate feature binding. We investigated whether suppressing cholinergic activity through moderate alcohol consumption in healthy humans affects behavioral measures of feature binding in visual perception and across perception and action. Indeed, evidence of the binding of shape and color, and of shape and location, of visual objects disappeared after alcohol consumption, whereas bindings between object features and the manual response were unaffected.
Abstract: In 3 dual-task experiments, the relationship between primary-task response (R1) and secondary-task response (R2) was varied. In general, R1-left responses were faster when followed by the word one, and right responses were faster when followed by the word two. This backward-compatibility (BWC) effect indicated (a) that activation of R2 was not delayed until R1 selection was completed, and (b) that activation of the vocal responses was accompanied by the automatic activation of magnitude codes, known to be associated with spatial left-right codes (spatial-numerical association of response codes [the SNARC effect]). These findings supported the hypotheses (a) that BWC effects persist even with irrelevant R1-R2 overlap, (b) that the SNARC effect is based on associations between magnitude and spatial representations underlying response processing, and (c) that the production and perception of magnitudes relies on common codes.
Abstract: The primate brain codes perceived events in a distributed fashion, which raises the question of how the codes referring to the same event are related to each other. Recent findings suggest that they are integrated into 'object files', episodic bindings of object-related information. However, the problem of integrating distributed codes is not restricted to perception but applies to action planning and sensorimotor processing as well. Here I argue that the brain addresses these problems by creating multi-layered networks of bindings - 'event files' - that temporarily link codes of perceptual events, the current task context, and the actions performed therein. These bindings produce systematic but often surprising and counter-intuitive interactions between, and impairments in, perception and action planning.
Abstract: Gains and losses in visual search were studied across the life span in a representative sample of 298 individuals from 6 to 89 years of age. Participants searched for single-feature and conjunction targets of high or low eccentricity. Search was substantially slowed early and late in life, age gradients were more pronounced in conjunction than in feature search, and all age groups were uniformly affected by eccentricity manipulations. However, developmental and aging trends were distinctly asymmetrical: Children's performance was particularly affected by the mere presence of distractors; whereas in late life, performance was particularly impaired on target-absent trials and with increasing numbers of distractors. The implications for life span theories of cognitive and attentional development and for cognitive-speed and inhibitory-control accounts are discussed.
Abstract: Because of attentional limitations, the human visual system can process for awareness and response only a fraction of the input received. Lesion and functional imaging studies have identified frontal, temporal, and parietal areas as playing a major role in the attentional control of visual processing, but very little is known about how these areas interact to form a dynamic attentional network. We hypothesized that the network communicates by means of neural phase synchronization, and we used magnetoencephalography to study transient long-range interarea phase coupling in a well studied attentionally taxing dual-target task (attentional blink). Our results reveal that communication within the fronto-parieto-temporal attentional network proceeds via transient long-range phase synchronization in the beta band. Changes in synchronization reflect changes in the attentional demands of the task and are directly related to behavioral performance. Thus, we show how attentional limitations arise from the way in which the subsystems of the attentional network interact.
Abstract: Human skilled behavior requires preparatory processes that selectively make sensory and motor systems more efficient for perceiving the upcoming stimulus and performing the correct action. We review the literature concerning these preparatory processes as studied by response-cuing paradigm, and propose a model that accounts for the major findings. According to the Grouping Model, advance or precue information directs a dynamic process of subgroup making-that is, a process of stimulus- and response-set reconfiguration-whereby the internal representation of the task is simplified. The Grouping Model assigns a critical role to the unit of selection, with Gestalt factors and interresponse dependencies mediating the formation and strength of stimulus and response subgroups. In a series of five experiments, we manipulated perceptual and motoric grouping factors, and studied their independent and interactive effects on the pattern of precuing benefits. Generally, the results were consistent with the Grouping Model's account of response-cuing effects.
Abstract: When subjects switch between two tasks, performance is slower after a task switch than after a task repetition. We report five experiments showing that a large part of these "task-shift-costs" cannot be attributed to a control operation, needed to configure the cognitive system for the upcoming task (e.g., ). In all experiments subjects switched between picture-naming and word-reading. We presented different stimuli either in just one of the two tasks, or in both of them. Shift-costs were larger for stimuli presented in both tasks than for those presented in only one task, even after more than 100 intervening trials between prime and probe events. We suggest (as proposed by ) that stimuli acquire associations with the tasks in which they occur. When the current task activation is weak, as on a switch of tasks, stimuli can trigger retrieval of the associated, competing task, provoking larger time costs.
Abstract: This study examined how 1 symbol is selected to control the allocation of attention when several symbols appear in the visual field. In Experiments 1-3, the critical target feature was color, and it was found that uninformative central arrows that matched the color of the target were selected and produced unintentional shifts of attention (i.e., involuntary, initiated slowly, producing long-lasting facilitatory effects). Experiment 4 tested whether such selection is the result of an attentional filter or of a competition bias due to a match of incoming information against integrated object representations stored in working memory. Here, the critical feature was shape and color was irrelevant, but matching color arrows were still selected. Thus, features of objects in working memory will bias the selection of symbols in the visual field, and such selected symbols are capable of producing unintentional shifts of attention. ((c) 2003 APA, all rights reserved)
Abstract: Spatial information is assumed to play a central, organizing role in object perception and to be an important ingredient of object representations. Here, evidence is provided to show that automatically integrated spatial object information is also functional in guiding spatial action. In particular, retrieving nonspatial information about a previewed object facilitates responses that spatially correspond to this object. This is true whether the object is still in sight or has already disappeared. So, forming an object representation entails the integration and storage of action-related information concerning the action that the object affords.
Abstract: Participants were required to switch among randomly ordered tasks, and instructional cues were used to indicate which task to execute. In Experiments 1 and 2, the participants indicated their readiness for the task switch before they received the target stimulus; thus, each trial was associated with two primary dependent measures: (1) readiness time and (2) target reaction time. Slow readiness responses and instructions emphasizing high readiness were paradoxically accompanied by slow target reaction time. Moreover, the effect of task switching on readiness time was an order of magnitude smaller then the (objectively estimated) duration required for task preparation (Experiment 3). The results strongly suggest that participants have little conscious awareness of their preparedness and challenge commonly accepted assumptions concerning the role of consciousness in cognitive control.
Abstract: Voluntary action is goal-directed and therefore depends on the ability to learn associations between movements and their perceivable consequences. The neural substrate of this ability was investigated with H2(15O) positron emission tomography (PET). Healthy adults first learned that self-initiated keypresses were consistently followed by certain tones (i.e., action effects). During PET imaging, participants listened to varied ratios of action-effect tones and neutral tones without performing any movement. The caudal supplementary motor area and the right hippocampus increased their activity with the frequency of action-effect tones, suggesting that both cortical areas play a role in linking the consequences of an action and the action itself. This integration process represents a highly flexible mechanism that helps to promote the learning, automatization, and control of voluntary
Abstract: In contradiction to stimulus-response- (S-R-) translation bottleneck models of dual-task control, stimulus processing in a primary task is affected by its compatibility with the response in a secondary, later performed task (Hommel, 1998a)- an indication of parallel S-R translation. Here we show that this backward-compatibility effect is independent of working-memory load, whether this is induced by an extra memory task (Experiment 1) or by increasing the number of S-R alternatives in the primary task (Experiment 2). However, backward effects occur even when the secondary task is no longer carried out (Experiment 3) and they are strongly affected by the inconsistency of previously used S-R mappings (Experiment 4). These findings suggest that S-R translation is (or can be) capacity-independent and automatic even under multiple-task conditions, and that it is mediated by direct S-R associations that emerge after only little practice.
Abstract: According to the authors' 2-phase model of action control, people first incidentally acquire bidirectional associations between motor patterns and movement-contingent events and then intentionally use these associations for goal-directed action. The authors tested the model in 4 experiments, each comprising an acquisition phase, in which participants experienced co-occurrences between left and right keypresses and low- and high-pitched tones, and a test phase, in which the tones preceded the responses in forced- and free-choice designs. Both reaction time and response frequency in the test phase depended on the learned associations, indicating that presenting a tone activated the associated response. Results are interpreted as evidence for automatic action-outcome integration and automatic response priming through learned action effects. These processes may be basic for the control of voluntary action by the anticipation of action goals.
Abstract: It has been argued that two distinct maps of visual space are formed: a cognitive map that is susceptible to illusions, and a motor map that represents the physical world veridically. In the present study, subjects responded to a nonspatial attribute of a visual target stimulus by pressing a left or right key, while an illusory horizontal displacement of the target was induced. A Simon-type effect was obtained to the induced target motion or position shift-that is, responses were faster when the illusory target motion or location corresponded to the response position. Further experiments indicated that the observed effects cannot be accounted for by attentional shifts. These results suggest that the content of the cognitive map does not only influence perceptual judgments but is also responsible for the automatic activation of response codes. In other words, perception and action seem to be fed by a common, cognitively penetrable, spatial representation.
Abstract: Traditional approaches to human information processing tend to deal with perception and action planning in isolation, so that an adequate account of the perception-action interface is still missing. On the perceptual side, the dominant cognitive view largely underestimates, and thus fails to account for, the impact of action-related processes on both the processing of perceptual information and on perceptual learning. On the action side, most approaches conceive of action planning as a mere continuation of stimulus processing, thus failing to account for the goal-directedness of even the simplest reaction in an experimental task. We propose a new framework for a more adequate theoretical treatment of perception and action planning, in which perceptual contents and action plans are coded in a common representational medium by feature codes with distal reference. Perceived events (perceptions) and to-be-produced events (actions) are equally represented by integrated, task-tuned networks of feature codes--cognitive structures we call event codes. We give an overview of evidence from a wide variety of empirical domains, such as spatial stimulus-response compatibility, sensorimotor synchronization, and ideomotor action, showing that our main assumptions are well supported by the data.
Abstract: The present study reports four pairs of experiments that examined the role of nonpredictive (i.e., task-irrelevant) symbolic stimuli on attentional orienting. The experiments involved a simple detection task, an inhibition of return (IOR) task, and choice decision tasks both with and without attentional bias. Each pair of experiments included one experiment in which nonpredictive arrows were presented at the central fixation location and another experiment in which nonpredictive direction words (e.g., "up," "down," "left," "right") were presented. The nonpredictive symbolic stimuli affected responses in all experiments, with the words producing greater effects in the detection task and the arrows producing greater effects in the IOR and choice decision tasks. Overall, the present findings indicate that there is a strong connection between the overlearned representations of the meaning of communicative symbols and the reflexive orienting of visual attention.
Abstract: Two experiments were performed to investigate the organization of spatial information in perception and memory. Participants were confronted with map-like configurations of objects which were grouped by color (Experiment 1) or shape (Experiment 2) so as to induce cognitive clustering. Two tasks were administered: speeded verification of spatial relations between objects and unspeeded estimation of the Euclidean distance between object pairs. In both experiments, verification times, but not distance estimations, were affected by group membership. Spatial relations of objects belonging to the same color or shape group were verified faster than those of objects from different groups, even if the spatial distance was identical. These results did not depend on whether judgments were based on perceptually available or memorized information, suggesting that perceptual, not memory processes were responsible for the formation of cognitive clusters.
Abstract: In bottleneck models of overlapping-task performance, stimulus-response translation for secondary tasks is postponed until the primary response is selected. If this is so, then compatibility between the secondary and primary responses, or between the secondary response and the primary stimulus, should not affect primary-task performance. Yet such effects were demonstrated in 5 dual-task experiments combining primary manual and secondary vocal tasks: Pronounced effects of compatibility between the secondary and primary response and between the secondary response and primary stimulus were found on primary-task performance. The latter effect was also found with the lowest level of an extensive stimulus onset asynchrony variation, when the secondary task was not speeded, and even when the 2 tasks were performed on different trials. Findings suggest that secondary responses were activated before primary response selection was completed and thus support an automatic-translation hypothesis holding that, although eventual response selection may be serial, stimulus-response translation is performed in parallel.
Abstract: This contribution is devoted to the question of whether action-control processes may be demonstrated to influence perception. This influence is predicted from a framework in which stimulus processing and action control are assumed to share common codes, thus possibly interfering with each other. In 5 experiments, a paradigm was used that required a motor action during the presentation of a stimulus. The participants were presented with masked right- or left-pointing arrows shortly before executing an already prepared left or right keypress response. We found that the identification probability of the arrow was reduced when the to-be-executed reaction was compatible with the presented arrow. For example, the perception of a right-pointing arrow was impaired when presented during the execution of a right response as compared with that of a left response. The theoretical implications of this finding as well as its relation to other, seemingly similar phenomena (repetition blindness, inhibition of return, psychological refractory period) are discussed.
Abstract: Reaction time is known to depend on spatial stimulus-response compatibility in both the horizontal and the vertical dimensions. However, if both dimensions are varied in the same task, horizontal but not vertical compatibility affects performance, even if subjects are instructed to attend to the vertical dimension only (Nicoletti & Umiltà , 1984). Experiment 1 compared the effect of horizontal and vertical instructions in a task with left-versus right-handed key responses placed at a top versus bottom location. A horizontal-prevalence effect was observed only with a horizontal, and not with a vertical, instruction. This suggests that subjects might not have heeded the vertical instruction in the Nicoletti and Umiltà study but instead attended to the horizontal dimension. Experiment 2 did not yield any horizontal prevalence with one-handed responses (joystick movements). This indicates that top-bottom codes become ineffective only if the responses suggest an exclusively horizontal response coding. In sum, results demonstrated multiple spatial coding of stimuli and responses under appropriate conditions and suggest that the right-left codes do not dominate the top-bottom spatial codes.
Abstract: Actions have been assumed to be cognitively represented by codes of relevant action features. Six experiments investigated whether irrelevant action features--conditioned response-contingent auditory events--are also coded and integrated into action codes. Subjects responded to visual stimuli by pressing a left-versus right-hand button or by touching a single key once versus twice. Responses produced certain action effects: tones on the left versus the right or tones of low versus high pitch. After subjects had some practice, an "inducing stimulus" was presented together with the reaction stimulus; this inducing stimulus shared features with the action effect of the correct or incorrect response. If action effects were integrated into action codes, inducing stimuli should activate or prime the associated response. Indeed, substantial effects of correspondence or compatibility between inducing stimuli and irrelevant action effects were found in a variety of tasks. Results are interpreted as evidence for an automatic integration of information about action effects and taken as support of an action-concept model of action-effect integration and stimulus-response compatibility.
Abstract: Two experiments investigated whether the Simon effect (i.e., faster responses to spatially corresponding than to noncorresponding stimuli, with stimulus location being irrelevant) is affected by the frequency of noncorrespondence trials. Stimulus discriminability (Experiment 1) and immediate or delayed stimulus formation (Experiment 2) was varied in order to manipulate the temporal relationship between coding of the relevant stimulus information and of stimulus location. As was expected, the Simon effect decreased from high to low discriminability and from immediate- to delayed-stimulus formation. This is consistent with the notion of a gradual decay of location-induced response-code activation. Moreover, the Simon effect decreased with increasing frequency of noncorrespondence trials and was even reversed with higher frequency. This demonstrates strategic preparation of stimulus processing and/or response selection based on irrelevant location information. However, frequency did not modify the interaction between S-R correspondence and stimulus discriminability or stimulus formation, this suggesting that code decay is not a result of a strategy, but an automatic process.
Abstract: Choice-reaction time is known to depend on the spatial correspondence of stimulus and response, even if the stimulus location is irrelevant to the task (Simon effect). An experiment investigated whether this effect depends on stimulus complexity--i.e., on whether properties of the stimulus render stimulus discrimination easy or difficult. It was hypothesized that high demands on discrimination slow down the processing of stimulus identity in relation to location, so that the facilitating or conflicting location code has more time to decay, thus losing impact on response selection. In fact, the results revealed an effect or irrelevant spatial S-R correspondence with easy, but not with difficult, stimulus discrimination. This finding resolves an apparent contradiction between the results of several previous experiments on the Simon effect.
Abstract: It has been claimed that spatial attention plays a decisive role in the effect of irrelevant spatial stimulus-response correspondence (i.e., the Simon effect), especially the way the attentional focus is moved onto the stimulus (lateral shifting rather than zooming). This attentional-movement hypothesis is contrasted with a referential-coding hypothesis, according to which spatial stimulus coding depends on the availability of frames or objects of reference rather than on certain attentional movements. In six experiments, reference objects were made available to aid spatial coding, which either appeared simultaneously with the stimulus (Experiments 1-3), or were continuously visible (Experiments 4-6). In contrast to previous experiments and to the attentional predictions, the Simon effect occurred even though the stimuli were precued by large frames surrounding both possible stimulus positions (Experiment 1), even when the reference object's salience was markedly reduced (Experiment 2), or when the precueing frames were made more informative (Experiment 3). Furthermore, it was found that the Simon effect is not reduced by spatial correspondence between an uninformative spatial precue and the stimulus (Experiment 4), and it does not depend on the location of spatial precues appearing to the left or right of both possible stimulus locations (Experiment 5). This was true even when the precue was made task-relevant in order to ensure attentional focusing (Experiment 6). In sum, it is shown that the Simon effect does not depend on the kind of attentional operation presumably performed to focus onto the stimulus. It is argued that the available data are consistent with a coding approach to the Simon effect which, however, needs to be developed to be more precise as to the conditions for spatial stimulus coding.
