Jochen Müsseler Full Professor for Work and Cognitive Psychology at the RWTH Aachen University, Germany
Research Interests: Perception of space and time, selective attention, perception-action interactions, dual-task performance, stimulus-response compatibility, cognitive ergonomics
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Abstract: When using a tool, proximal action effects (e.g., the hand movement on a digitizer tablet) and distal action effects (e.g., the cursor movement on a display) often do not correspond to or are even in conflict with each other. In the experiments reported here, we examined the role of proximal and distal action effects in a closed loop task of sensorimotor control. Different gain factors perturbed the relation between hand movements on the digitizer tablet and cursor movements on a display. In the experiments, the covert hand movement was held constant, while the cursor amplitude on the display was shorter, equal, or longer, and vice versa in the other condition. When participants were asked to replicate the hand movement without visual feedback, hand amplitudes varied in accordance with the displayed amplitudes. Adding a second transformation (Experiment 1: 90°-rotation of visual feedback, Experiment 2: 180°-rotation of visual feedback) reduced these aftereffects only when the discrepancy between hand movement and displayed movement was obvious. In conclusion, distal action effects assimilated proximal action effects when the proprioceptive/tactile feedback showed a feature overlap with the visual feedback on the display.
Abstract: Two experiments examined the hypothesis that preparing an action with a specific affective connotation involves the binding of this action to an affective code reflecting this connotation. This integration into an action plan should lead to a temporary occupation of the affective code, which should impair the concurrent representation of affectively congruent events, such as the planning of another action with the same valence. This hypothesis was tested with a dual-task setup that required a speeded choice between approach- and avoidance-type lever movements after having planned and before having executed an evaluative button press. In line with the code-occupation hypothesis, slower lever movements were observed when the lever movement was affectively compatible with the prepared evaluative button press than when the two actions were affectively incompatible. Lever movements related to approach and avoidance and evaluative button presses thus seem to share a code that represents affective meaning. A model of affective action control that is based on the theory of event coding is discussed.
Abstract: The impact of sensorimotor transformations with graphical input devices is surveyed with regard to action control. Recent evidence lets us assume that the distal action effect (the moving cursor) rather than the proximal action effect (the moving hand) determines the efficiency of tool use. In Experiment 1, different gains were explored with a touchpad and a mini-joystick. In correspondence with our assumptions the results revealed evidence that Fittsâ law holds for distal actionâeffect movements, but less for proximal actionâeffect movements. Most importantly, this was not only true for the touchpad but also for the mini-joystick. We further found a more efficient use of the touchpad in comparison to the mini-joystick when a high gain was used. In Experiment 2, the dominance of the action effect on motor control was confirmed in an experiment with a digitiser tablet. The tablet amplitude was held constant, but again, movement times followed the perceived index of difficulty on the display. It is concluded that Fittsâ law did not rely on the movements of the motor system, but on the distal action effects on the display (changes in visual space). Distal actionâeffect control plays an important role in understanding the constraints of the acquisition and application of tool transformations.
Abstract: Objective: The study focuses on potential compatibility relationships when simple lever tools are used.
Background: Spatial compatibility between stimuli and responses determines performance. However, many tasks require the use of simple tools, such as levers that transform hand movements into tool movements.We explore with such a tool whether and how the correspondence or noncorrespondence between stimulus-side and hand movement (stimulus-response compati- bility), between stimulus-side and tool-effect movement (stimulus-effect compatibility), and/or between hand movement and tool-effect movement (response-effect compatibility) affects performance.
Method: U-shaped and inverted-U-shaped levers were used as tools, allowing us to examine the contribution of each compatibility relationship to response times and errors without any confounds and omissions.
Results: Responding was delayed and error prone when the hand movement and the movement of the effect point of the tool did not correspond. Effects of stimulus-response compatibility and stimulus-effect compatibility were observed only when the hand movement direction remained untransformed in the tool-effect movement.
Conclusion: The results point out that the inversion or noninversion of tool-effect movements plays an underlying role when handling a tool.
Application: Potential applications of this research include the prediction and possibly manipulation of unwanted behavioral tendencies in laparoscopic surgery and other lever movements.
Abstract: Eye movements are a key behavior for visual information processing in traffic situations and for vehicle control. Previous research showed that effective ways of eye guidance are related to better hazard perception skills. Furthermore, hazard perception is reported to be faster for experienced drivers as compared to novice drivers. However, little is known whether this difference can be attributed to the development of visual orientation, or hazard processing. In the present study, we compared eye movements of 20 inexperienced and 20 experienced drivers in a hazard perception task. We separately measured (a) the interval between the onset of a static hazard scene and the first fixation on a potential hazard, and (b) the interval between the first fixation on a potential hazard and the final response. While overall RT was faster for experienced compared to inexperienced drivers, the scanning patterns revealed that this difference was due to faster processing after the initial fixation on the hazard, whereas scene scanning times until the initial fixation on the hazard did not differ between groups.
Abstract: When observers are asked to localize the peripheral position of a small probe with respect to the mid-position of a spatially extended comparison stimulus, they tend to judge the probe as being more peripheral than the mid-position of the comparison stimulus. This relative mislocalization seems to emerge from differences in absolute localization, that is the comparison stimulus is localized more towards the fovea than the probe. The present study compared saccadic behaviour and relative localization judgements in three experiments and determined the quantitative relationship between both measures. The results showed corresponding effects in localization errors and saccadic behaviour. Moreover, it was possible to estimate the amount of the relative mislocalization by means of the saccadic amplitude.
Abstract: Previous studies yielded evidence that the precision, with which stimuli are localized in the visual periphery, is improved under conditions of focused attention. The present study examined whether focused attention is able to correct a mislocalization recently observed with successively presented stimuli: when observers are asked to localize the peripheral position of a briefly presented target with respect to a previously presented comparison stimulus, they tended to judge the target as being more towards the fovea than was its actual position. In three experiments the mislocalization was tested under conditions with focused and distributed attention. Results revealed that the mislocalization increased with distributed attention and disappeared when stimuli appeared consistently at predictable positions and thus under conditions of focused attention. However, when a procedure with a trial-by-trial cueing was applied the mislocalization was only reduced, but not wiped out completely. In a recently developed dynamic field model consisting of interacting excitatory and inhibitory neuronal cell populations the results were explained as an attentional modulation of spontaneous (baseline) levels of neural activity.
Abstract: World knowledge influences how we perceive the world. This study shows that this influence is at least partly mediated by declarative memory. Dutch and German participants categorized hues from a yellow-to-orange continuum on stimuli that were prototypically orange or yellow and that were also associated with these color labels. Both groups gave more âyellowâ responses if an ambiguous hue occurred on a prototypically yellow stimulus. The language groups were also tested on a stimulus (traffic light) that is associated with the label orange in Dutch and with the label yellow in German, even though the objective color is the same for both populations. Dutch observers categorized this stimulus as orange more often than German observers, in line with the assumption that declarative knowledge mediates the influence of world knowledge on color categorization.
Abstract: Effects of spatial stimulus-response compatibility are often attributed to automatic position-based activation of the response elicited by a stimulus. Three experiments examined this assumption in natural scenes. In Experiments 1 and 2, participants performed simulated driving, and a person appeared periodically on either side of the road. Participants were to turn toward a person calling a taxi and away from a person carelessly entering the street. The spatially incompatible response was faster than the compatible response, but neutral stimuli showed a typical benefit for spatially compatible responses. Placing the people further in the visual periphery eliminated the advantage for the incompatible response and showed an advantage for the compatible response. In Experiment 3, participants made left-right joystick responses to a vicious dog or puppy in a walking scenario. Instructions were to avoid the vicious dog and approach the puppy or vice versa. Results again showed an advantage for the spatially incompatible response. Thus, the typically observed advantage of spatially compatible responses was reversed for dangerous situations in natural scenes.
Abstract: Numerous studies found superior performance when the irrelevant location of a stimulus and response location were corresponding than when they were not corresponding (Simon effect), suggesting that stimulus location is processed in an obligatory manner. The present study compared Simon effects from the location of a relevant (i.e., to-be-attended) object to those from the location of an irrelevant (i.e., to-be-ignored) object. In four experiments, participants were presented with a rectangular frame and a square, with the relevant object in green or red color and the irrelevant object in gray or white color. Participants' task was to respond with a lateral keypress to the color of the relevant object, and we varied spatial correspondence between the location of the relevant or the irrelevant object and the response, respectively. Results consistently showed larger Simon effects from the location of the relevant than from the irrelevant object, even when the irrelevant object was made very salient. These results suggest that location processing is largely confined to relevant (i.e., attended) objects, stressing the role of attention shifts for location encoding.
Abstract: The present study examined what participants perceive of their hand movements when using a tool. In the experiments different gains for either the x-axis or the y-axis perturbed the relation between hand movements on a digitizer tablet and cursor movements on a display. As a consequence of the perturbation participants drew circles on the display while their covered hand movements followed either vertical or horizontal ellipses on the digitizer tablet. When asked to evaluate their hand movements, participants were extremely uncertain about their trajectories. By varying the amount of visual feedback, findings indicated that the low awareness of one's own movements originated mainly from an insufficient quality of the humans' tactile and proprioceptive system or from an insufficient spatial reconstruction of this information in memory.
Abstract: When observers were asked to localize the peripheral position of a briefly presented target with respect to a previously presented comparison stimulus, they tended to judge the target as being more towards the fovea than the comparison stimulus. Three experiments revealed that the mislocalization only emerged when the comparison stimulus and the target were presented successively. Varying the temporal interval between stimuli showed that the mislocalization reversed with longer stimulus-onset asynchronies. Further, the mislocalization was increased with a decrease of the spatial distance between stimuli. These findings suggested that the mislocalization originated from local excitatory and inhibitory mechanisms. Corroborating this idea a neuronal dynamic field model was successfully developed to account for the findings.
Abstract: Evidence for motion extrapolation at motion offset is scarce. In contrast, there is abundant evidence that subjects mentally extrapolate the future trajectory of weak motion signals at motion offset. Further, pointing movements overshoot at motion offset. We believe that mental and sensorimotor extrapolation is sufficient to solve the problem of perceptual latencies. Both present the advantage of being much more flexible than motion extrapolation.
Abstract: Responding to a stimulus is faster and more accurate when stimulus location and response location spatially correspond than when they do not correspond (stimulus-response compatibility). In five experiments this standard compatibility effect is examined when using a T-shaped lever as a tool. Handling the lever allowed distinguishing body-related action effects (e.g., the tactile feedback from the moving finger) from external action effects (e.g., reaching at the stimulus with the lever's end-point). Results showed that the spatial relationship between stimulus and the direction of the hand movement (S-R compatibility) as well as the relationship between the stimulus and the functional end-points of the tool (S-E compatibility) determine performance. More precisely, responses were fast and less error prone when both kinds of compatibility did correspond than when they did not correspond.
Abstract: In the Fröhlich effect, the perceived onset of a moving stimulus is displaced in the direction of motion. Previously, we observed that pointing movements produced a Fröhlich effect only when the onset position was highly predictable. Here, we show that relative judgments are not affected by spatial predictability if the relative judgment task is performed in isolation. However, when the two tasks vary randomly from trial to trial, effects of spatial predictability carry over to the perceptual task. Thus, observers' intentions before stimulus onset determine the way position signals are processed. An account in terms of sensory and motor maps is discussed.
Abstract: The increase of a "graying" society is apparent in recent decades and as such, the attention of marketing and product design is more and more focused on older users of technical devices. The study addresses the relevance of hardware and software design in human-computer interaction of older users. It was found that performance significantly increased (up to 3 times) with easier sensumotor transformation and easier task type. However, this was more prominent in middle-aged users than in younger users. Task difficulty revealed a rather unspecific impact on performance (43%), and was equally apparent in both age groups. Recommendations derived from this review show that older users will profit most from touch based or mouse operated interfaces. Additionally, easy icon and menu designs are often missed and will become more and more important for older users.
Notes: LECTURE NOTES IN COMPUTER SCIENCE xD;0302-9743
Abstract: Objective: We explored constraints in responding to spatially variable stimuli when hand movements are transformed into inverse movements of a tool. Background: Generally, the spatial compatibility between stimuli and responses is a powerful determinant of performance. However, many tasks require the use of simple tools such as first-class levers that transform hand movements into inverted movements of a tool. What types of compatibility effects arise with such tools? Method: Participants moved the tip of a pointer to the left or fight according to the color of a stimulus. The pointer was manipulated either directly, so that a hand movement caused a pointer movement in the corresponding direction, or indirectly, so that the hand moved the pointer in the opposite direction. Results: Responding was faster when the location of stimulus and the movement direction of the tool corresponded than when they did not correspond, independent of the movement direction of the hand. This occurred when stimulus location was task relevant (Experiment 1) as well as when it was task irrelevant (Experiment 2). Furthermore, responding was delayed when the hand and the relevant end of the tool moved in noncorresponding rather than corresponding directions. Conclusion: These results point to two distinct compatibility effects in tool use: one that relates to the transformation of stimuli into goals and one that relates to the transformation of goals into movements. Application: Potential applications of this research include the prediction and possibly manipulation of unwanted "fulcrum effects" in laparoscopic surgery and other first-class lever movements.
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: This study deals with the problem of whether the processing of irrelevant location information in Simon-like tasks is triggered exogenously or endogenously. In Experiment 1, the primary task required one to press, as fast as possible, a left-hand-side key or a right-hand-side key (R1) to the pitch of a tone that was presented binaurally (S1). The secondary task required identifying, without time constraints, a visual stimulus (S2) that appeared randomly to the left or right of screen center. Results showed that there was a correspondence (i.e., a cross-task Simon effect) between the location of R1 and the location of S2 when S2 was presented alone. The cross-task Simon effect became much smaller (and insignificant) when a noise stimulus was presented contralateral to S2. Experiment 2 was similar to Experiment 1, except that S2 appeared unpredictably in only one-third of the trials. Results of Experiment 2 closely replicated those of Experiment 1: the cross-task Simon effect was much greater when S2 was presented alone. Experiment 3 differed from Experiment 1 because S2 had to be processed in only one-third of the trials, in which its identity was to be reported. In the remaining two-thirds of the trials, participants could ignore S2. Results confirmed that the cross-task Simon effect was much greater when S2 was presented alone. In contrast, it did not matter whether S2 had to be processed or not. In conclusion, the present study supports the hypothesis that the task-irrelevant spatial code of the stimulus is formed automatically, likely through an exogenously triggered selection. The role of endogenously initiated selection, if any, is much less important.
Abstract: The Simon effect denotes superior performance when stimulus and response positions correspond than when they do not, even when stimulus position is irrelevant. Usually, this effect is attributed to the automatic formation of a spatial stimulus code that interferes with response selection. Recent evidence, however, called the hypothesis of automatic processing of stimulus position into question. The present study aimed at providing a strong test of this hypothesis. In two experiments, a dual-task procedure was employed. The primary task was an auditory-manual four-choice task (S1-R1 task). The secondary task was a visual encoding task (S2-R2 task), and S2 followed S1 with a variable stimulus onset asynchrony (SOA). Horizontal position of S2, which was irrelevant for both tasks, was also varied, and the effect of spatial S2-R1 correspondence was investigated. Experiment 1 showed dual-task impairment in visual encoding, and a cross-task Simon effect at short SOAs. That is, S2 position affected R1 selection, although less capacity was available for deliberately processing S2 position. In addition, Experiment 2 revealed the absence of the cross-task Simon effect when the target appeared simultaneously with a contralateral distractor. Together, the results suggest that encoding of stimulus position can run automatically, on the basis of an exogenous attention shift towards stimulus location.
Abstract: The missing-letter effect refers to the phenomenon that letters are more difficult to detect in common function words (such as the) than in content words. Assuming that the missing-letter effect is diagnostic of the extraction of text structure, we exploited a special feature of German--the convention to capitalize the initial letter of nouns. Given the great flexibility of word order in German, it was proposed that this convention might help readers specify the structure of the sentence. Therefore orthographic variations that violate the capitalization rules should disrupt structure extraction and should result in a reduced missing-letter effect. The results indicated that: 1) capitalization of function words eliminated the missing-letter effect, but not at the beginning of a sentence; 2) A missing-letter effect occurred when the capitalization of the first letter was correct, but was followed by typecase alternation, and also when the size of the initial letters was relatively large for function words, but relatively small for content words. The results were discussed with respect to the possible contributions of visual familiarity, structural role, and processing time to the missing-letter effect, taking into account that a capitalized initial letter conveys significant information about the word class for German readers. Thus, the present results indicate that readers take advantage not only of function words but of any other information (here the capitalization of nouns) that helps to extract the structure of a sentence.
Abstract: Previous dual-task studies showed that the selection and/or execution of a response interfere with concurrent visual encoding (action-induced blindness). Four experiments examined how the lateralization of stimuli and responses might affect action-induced blindness. Participants responded to tones (S1) by pressing keys with the left or right hand (R1), and simultaneously identified stimuli (S2) presented to the left or right visual field. Results revealed a complex pattern of cross-talk effects between response preparation and visual encoding. Firstly, preparing a response generally impaired concurrent visual encoding. Secondly, action-induced blindness was equally present for ipsilaterally and contralaterally presented stimuli. Thirdly, response preparation facilitated processing of visual stimuli at ipsilateral locations, probably a case of action-centered attention. Finally, the facilitatory effect of R1-S2 correspondence on visual encoding was complemented by a S2-R1 correspondence effect on response execution. Thus, acting while seeing can have both beneficial and detrimental effects on identification performance at the same time.
Abstract: Three experiments investigated whether the repeated-letter inferiority effect (RLIE) and repetition blindness (RB) are identical phenomena or not and how the RLIE can be reconciled with the flanker compatibility effect (FCE). Participants reported a masked target and ignored an unmasked distractor. We manipulated the type of distractor (identical, alternative target, or neutral), the order of presenting distractor and target, and the predictability of target location. When distractors preceded the targets, distractors identical to the target always caused deficits in target processing (i.e., RB). With simultaneous presentation, identical distractors caused deficits (i.e., an RLIE) for unpredictable target locations only. Yet the RLIE was significantly smaller than RB. This result suggests that simultaneously presented stimuli are identified serially, in random order, if target position is unpredictable. As a result, RB arises only in the 50% of all trials with identical distractors in which the distractor is identified before the target. With simultaneous presentation and predictable target location, however, parallel processing of targets and distractors was possible that gave rise to an FCE in recognition accuracy. Analyses of false alarm rates revealed no evidence of significant response biases.
Abstract: It is known that observers make localization errors in the direction of motion when asked to localize the perceived onset position of a moving target (Fröhlich effect). However, recent studies also revealed the contrary: In the onset repulsion effect, the error is opposite to the direction of motion. In four experiments we demonstrate that the conflict between these findings is resolved by considering the trial context: when the stimuli appeared at predictable positions to the left or right of fixation, pointing responses to the perceived onset position were displaced in movement direction. In contrast, when the stimuli appeared at unpredictable positions in the visual field, pointing errors were displaced opposite to motion or at least drastically reduced. Thus, localization of the perceived onset position varies with the trial context.
Abstract: When observers are asked to localize the peripheral position of a target with respect to the midposition of a spatially extended comparison stimulus, they tend to mislocalize the target as being more outer than the midposition of the comparison stimulus (cf. Musseler, Van der Heijden, Mahmud, Deubel, & Ertsey, 1999). For explaining this finding, we examined a model that postulates that in the calculation of perceived positions two sources are involved, a sensory map and a motor map. The sensory map provides vision and the motor map contains information for saccadic eye movements. The model predicts that errors in location judgements will be observed when the motor map has to provide the information for the judgements. In four experiments we examined, and found evidence for, this prediction. Localization errors were found in all conditions in which the motor map had to be used but not in conditions in which the sensory map could be used.
Abstract: Behavioral experiments revealed an impairment in a perceptual task when a motor task has to be planned in parallel. In two event-related fMRI experiments healthy participants performed a GO-NOGO motor task and a visual identification task. Thus, we were able to investigate the influence of a motor task on visual identification. The paradigm allowed to compare visually identical trials with and without a concurrently performed motor response. In Experiment 1, the visual task focused on shape identification, whereas in Experiment 2, the visual task focused on color identification. We found an action-dependent BOLD response modulation in extrastriate visual areas (V3, V3A in Experiment 1 and additionally V4 in Experiment 2). Thus, results demonstrate that the planning of an action has modulatory effects in brain areas concerned with early processes in visual encoding.
Abstract: Vision evolved from the vital necessity to act in a dynamic environment. Following this view it is clear that perceptual processes and action planning are much more interlocked than is evident at first sight. This is especially evident in visual space perception; actions are performed in space and are guided and controlled by objects in spatial positions. Here we shortly introduce the three research camps dealing with the relationship between space perception and action: the ecological camp, the two-visual-systems camp, and the constructivist camp. We show that these camps emphasize and open different theoretical and empirical perspectives, but that they can be seen to complement each other. We end with an overview of the papers in this special issue.
Abstract: When observers localize the vanishing point of a moving target, localizations are reliably displaced beyond the final position, in the direction the stimulus was travelling just prior to its offset. We examined modulations of this phenomenon through eye movements and action control over the vanishing point. In Experiment 1 with pursuit eye movements, localization errors were in movement direction, but less pronounced when the vanishing point was self-determined by a key press of the observer. In contrast, in Experiment 2 with fixation instruction, localization errors were opposite movement direction and independent from action control. This pattern of results points at the role of eye movements, which were gathered in Experiment 3. That experiment showed that the eyes lagged behind the target at the point in time, when it vanished from the screen, but that the eyes continued to drift on the targets' virtual trajectory. It is suggested that the perceived target position resulted from the spatial lag of the eyes and of the persisting retinal image during the drift.
Abstract: When two speeded response tasks are performed in close succession, performance on the second task is usually impaired. Recently, an impairment has also been observed when the second task required only the visual identification of a stimulus. Thus, visual encoding seems to suffer from the need to share limited processing capacities with some processes in the first task. Yet, it is still unclear which particular processes in the first task compete with stimulus encoding in the second task. The present experiments further examined the influence of response planning and execution on visual encoding and found both content-nonspecific and content-specific interference. An event-coding account is proposed that posits structural and procedural overlap of response-planning and stimulus-encoding mechanisms.
Abstract: This study investigated the conditions under which the processing in a speeded response task interferes with concurrent processing in a visual encoding task. Three experiments used a dual-task paradigm, in which a speeded left or right response to a tone was combined with the identification of a masked left- or right-pointing arrow following the tone with variable SOA. Two additional experiments tested the impact of the presentation of pure tone on visual encoding. There were four major findings. First, an unspecific decrease in identification accuracy was observed with decreasing SOA. Second, a blindness to response-compatible stimuli was observed with speeded responses. Third, a specific interference was found between low- and high-pitched tones and left- or right-pointing arrows. Fourth, the specific tone-arrow interference modulated the specific response-arrow interference when the task allowed both to occur simultaneously. The present findings, which suggest both procedural and structural interference between response preparation and stimulus encoding, are discussed in terms of a two-stage model of action planning.
Abstract: In the Fröhlich illusion, judgements of the first position of a moving object are typically displaced in the direction of motion. The illusion has been obtained with linear motion of a small target, and with rotary motion of a spatially extended line. We compared judgements of the initial orientation of a small dot and a line that rotated around the point of fixation. The illusion was absent with the dot, whereas it was reliably obtained with the line. When the density of the line was reduced to two dots, the illusion persisted. However, the illusion was absent when a half-line extending to only one side from fixation was presented. We discuss the results with respect to two attentional accounts of the Fröhlich illusion and an account based on spatiotemporal integration.
Abstract: When observers pursue a moving target with their eyes, they use predictions of future target positions in order to keep the target within the fovea. It was suggested that these predictions of smooth pursuit (SP) eye movements are computed only from the visual feedback of the target characteristics. As a consequence, if the target vanishes unexpectedly, the eye movements do not stop immediately, but they overshoot the vanishing point. We compared the spatial and temporal features of such predictive eye movements in a task with or without intentional control over the target vanishing point. If the observers stopped the target with a button press, the overshoot of the eyes was reduced compared to a condition where the offset was computer generated. Accordingly, the eyes started to decelerate well before the target offset and lagged further behind the target when it disappeared. The involvement of intentionally-generated expectancies in eye movement control was also obvious in the spatial trajectories of the eyes, which showed a clear flexion in anticipation of the circular motion path we used. These findings are discussed together with neurophysiological mechanisms underlying the SP eye movements.
Abstract: When observers are asked to localize the onset or the offset position of a moving target, they typically make localization errors in the direction of movement. Similarly, when observers judge a moving target that is presented in alignment with a flash, the target appears to lead the flash. These errors are known as the Frohlich effect, representational momentum, and flash-lag effect, respectively. This study compared the size of the three mislocalization errors. In Experiment 1, a flash appeared either simultaneously with the onset, the mid-position, or the offset of the moving target. Observers then judged the position where the moving target was located when the flash appeared. Experiments 2 and 3 are exclusively concerned with localizing the onset and the offset of the moving target. When observers localized the position with respect to the point in time when the flash was presented, a clear mislocalization in the direction of movement was observed at the initial position and the mid-position. In contrast, a mislocalization opposite to movement direction occurred at the final position. When observers were asked to ignore the flash (or when no flash was presented at all), a reduced error (or no error) was observed at the initial position and only a minor error in the direction of the movement occurred at the final position. An integrative model is proposed, which suggests a common underlying mechanism, but emphasizes the specific processing components of the Frohlich effect, flash-lag effect, and representational momentum.
Abstract: When observers are asked to indicate the final position of a moving stimulus, their localizations are reliably displaced beyond the final position, in the direction the stimulus was traveling just prior to its offset. Recent experiments indicate that these localization errors depend on whether or not observers track the moving stimulus with eye-movements. If they track, there is a localization error; if not, the error reduces to zero. The present series of experiments investigated whether localization error might be due, in part, to the binding of the moving stimulus in an action plan. Experiment I utilized circular stimulus trajectories, and the eye tracking/no-tracking discrepancy revealed in previous studies was replicated. Experiment 2 required central fixation by all observers, and either the computer program (i.e. induction) or a button press by the observer (i.e. intention) produced the stimulus offset. The localizations made in the Intention condition were further in the direction of the planned action effect than those made in the Induction condition. Experiment 3 demonstrated these differences to be due to the intention to stop the stimulus, not the button press. And Experiment 4 revealed that action planning has its binding effect on the localization error for a duration that extends beyond the actual moment of action execution. In light of these data, an approach to perception-action coupling is proposed in which spatial perception and spatially directed action are modeled, not as input and output, respectively, but rather, as synergistically coupled control systems.
Abstract: This article examines the time course of a deficit in identifying a stimulus sharing a compatible feature with a response that is executed in parallel ("blindness to response-compatible stimuli," J. Musseler & B. Hommel, 1997a). In 5 experiments, participants performed a timed response, and the presentation point of time of a to-be-identified stimulus was varied in respect to response execution. A blindness effect was observed when the stimulus was presented between response cue offset and response execution. In contrast, the identification of a stimulus presented before the response cue or after response execution was not affected by stimulus-response compatibility-a finding that rules out a retention-based explanation. These results support an explanation that states that the perceptual processing of a stimulus feature is impaired as long as the shared perception-action feature code is integrated into the representation of a to-be-executed response.
Abstract: The judged final position of a moving stimulus has been suggested to be shifted in the direction of motion because of mental extrapolation (representational momentum). However, a perceptual explanation is possible: The eyes overshoot the final position of the target, and because of a foveal bias, the judged position is shifted in the direction of motion. To test this hypothesis, the authors replicated previous studies, but instead of having participants indicate where the target vanished, the authors probed participants' perceptual focus by presenting probe stimuli close to the vanishing point. Identification of probes in the direction of target motion was more accurate immediately after target offset than it was with a delay. Another experiment demonstrated that judgments of the final position of a moving target are affected by whether the eyes maintain fixation or follow the target. The results are more consistent with a perceptual explanation than with a memory account.
Abstract: First, we discuss issues raised with respect to the Theory of Event Coding (TEC)'s scope, that is, its limitations and possible extensions. Then, we address the issue of specificity, that is, the widespread concern that TEC is too unspecified and, therefore, too vague in a number of important respects. Finally, we elaborate on our views about TEC's relations to other important frameworks and approaches in the field like stages models, ecological approaches, and the two-visual-pathways model.
Abstract: Previous studies reported impairments in a perceptual task performed during the selection and execution of an action. These findings, however, always raise the question of whether the impairment actually reflects a reduction in perceptual sensitivity or whether it results only from an unspecific reduction in attentiveness given the perceptual task. Recent studies by the authors indicate that actions can also have a specific impact on perception in a dual-task situation. The identification of a left or right arrow is impaired when it appears during the execution of a compatible left or right keypress. In three experiments Signal Detection Theory is applied to test whether this impairment is also found in the sensitivity measure d' or whether it originates only from a response tendency. The results revealed a general lower d' for the identification of arrows that were compatible to simultaneously executed keypresses than for arrows that were incompatible. The bias measure c was small and/or did not differ between conditions. Additional analyses revealed that the impairment is due to a higher mean perceptual degradation of stimuli in the compatible condition and that it is restricted to the point in time when the central movement command is generated. Thus, actions actually seem able to affect perceptual processing.
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 judged final position of a moving stimulus has been suggested to be shifted in the direction of motion because of mental extrapolation (representational momentum). However, a perceptual explanation is possible: The eyes overshoot the final position of the target, and because of a foveal bias, the judged position is shifted in the direction of motion. To test this hypothesis, the authors replicated previous studies, but instead of having participants indicate where the target vanished, the authors probed participants' perceptual focus by presenting probe stimuli close to the vanishing point. Identification of probes in the direction of target motion was more accurate immediately after target offset than it was with a delay. Another experiment demonstrated that judgments of the final position of a moving target are affected by whether the eyes maintain fixation or follow the target. The results are more consistent with a perceptual explanation than with a memory account.
Abstract: This article examines the time course of a deficit in identifying a stimulus sharing a compatible feature with a response that is executed in parallel ("blindness to response-compatible stimuli," J. Müsseler & B. Hommel, 1997a). In 5 experiments, participants performed a timed response, and the presentation point of time of a to-be-identified stimulus was varied in respect to response execution. A blindness effect was observed when the stimulus was presented between response cue offset and response execution. In contrast, the identification of a stimulus presented before the response cue or after response execution was not affected by stimulus-response compatibility--a finding that rules out a retention-based explanation. These results support an explanation that states that the perceptual processing of a stimulus feature is impaired as long as the shared perception-action feature code is integrated into the representation of a to-be-executed response.
Abstract: Letters are more difficult to detect in function words than in content words, presumably because function words serve to cue sentential structure but recede to the background as meaning unfolds. This function disadvantage was found for the definite article in German for all three genders and all four cases, but it was more pronounced when the article appeared in a nominative noun phrase than in an object noun phrase. It was also more pronounced for the typical subject-predicate-object sentential format than for the object-predicate-subject sentential format and also when the definite article unequivocally specified the case of a phrase than when it was ambiguous. The results suggest that the structural frames established on line in reading are finely tuned to both phrase-level and sentence-level organization.
Abstract: Letters are more difficult to detect in function words than in content words, presumably because function words serve to cue sentential structure but recede to the background as meaning unfolds. This function disadvantage was found for the definite article in German for all three genders and all four cases, but it was more pronounced when the article appeared in a nominative noun phrase than in an object noun phrase. It was also more pronounced for the typical subject-predicate-object sentential format than for the object-predicate-subject sentential format and also when the definite article unequivocally specified the case of a phrase than when it was ambiguous. The results suggest that the structural frames established on line in reading are finely tuned to both phrase-level and sentence-level organization.
Abstract: Previous work has indicated that action-control processes can specifically influence perceptual processes. The identification of a left-or right-pointing arrow is impaired when it appears during the preparation and execution of a compatible left-right keypress (Musseler & Hommel, 1997a, b). The present study examines the role of the response-specifying cue in order to manipulate the coding of the action-control processes. Experiment 1 shows that the size of the perceptual impairment is not affected by whether the cue has high or little feature overlap with the to-be-performed response. Cues were omitted in Experiment 2 and participants generated their responses endogenously, but the perceptual impairment still occurred. Experiment 3 examines in more detail which feature of the response contributes to the effect. The results show that it needs both an intended action goal and a corresponding motor activity to bring about the perceptual impairment.
Abstract: It has often been reported that, in the presence of static reference stimuli, briefly presented visual targets are perceived as being closer to the fixation point than they actually are. The first purpose of the present study was to investigate whether the same phenomenon can be demonstrated in a situation without static reference stimuli. Experiment 1, with position naming as the task, showed that such a central shift is also observed under these conditions. This finding is of importance because it completes an explanation for central near-location errors in the partial-report bar-probe task. The second purpose of the present study was to provide an explanation for these central shifts. For this explanation information about the exact size of the central shift is required. In Exps. 2, 3, and 4, with cursor setting as the task, it was attempted to assess more precisely the size of the central shifts. These experiments revealed that two different factors determine the results in cursor setting tasks; a factor "target position" and a factor "cursor position." Experiment 5 showed that it is the point of fixation, not the fixation point. that serves, at least in part, as the reference point in this type of task. All the findings together allow us to conclude that the target positions are underestimated by about 10%. From vision research it is known that saccadic eye movements, performed for bringing a target in the fovea, also show an undershoot of about 10%. It is therefore concluded that the system in charge of saccadic eye movements also provides the metric in visual space within a single eye fixation.
Abstract: We studied the ability to localize flashed stimuli, using a relative judgment task. When observers are asked to localize the peripheral position of a probe with respect to the midposition of a spatially extended comparison stimulus, they tend to judge the probe as being more toward the periphery than is the midposition of the comparison stimulus. We report seven experiments in which this novel phenomenon was explored. They reveal that the mislocalization occurs only when the probe and the comparison stimulus are presented in succession, independent of whether the probe or the comparison stimulus comes first (Experiment 1). The size of the mislocalization is dependent on the stimulus onset asynchrony (Experiment 2) and on the eccentricity of presentation (Experiment 3). In addition, the illusion also occurs in an absolute judgment task, which links mislocalization with the general tendency to judge peripherally presented stimuli as being more foveal than they actually are (Experiment 4). The last three experiments reveal that relative mislocalization is affected by the amount of spatial extension of the comparison stimulus (Experiment 5) and by its structure (Experiments 6 and 7). This pattern of results allows us to evaluate possible explanations of the illusion and to relate it to comparable tendencies observed in eye movement behavior. It is concluded that the system in charge of the guidance of saccadic eye movements is also the system that provides the metric in perceived visual space.
Abstract: When participants are asked to localize the Ist position of a moving stimulus, they mislocalize it in the direction of the movement (Frohlich effect; F. W. Frohlich, 1923). This mislocalization points to a delay in the temporal sensation of a moving stimulus. However, the delay is in contrast to findings indicating a faster processing of moving stimuli. This potential dissociation was studied in 6 experiments. After establishing the effect spatially, different temporal tasks were examined under otherwise identical conditions. Simple as well as choice reaction times were shorter to moving than to stationary stimuli. Other tasks (choice reaction to structural features, temporal order judgment, and synchronization), however, produced opposite effects. Results support a view that the output of early stimulus processing directly feeds into the motor system, whereas the processing stages used, for example, for localization judgments are based on later integrative mechanisms.
Abstract: It has often been reported that, in the presence of static reference stimuli, briefly presented visual targets are perceived as being closer to the fixation point than they actually are. The first purpose of the present study was to investigate whether the same phenomenon can be demonstrated in a situation without static reference stimuli. Experiment 1, with position naming as the task, showed that such a central shift is also observed under these conditions. This finding is of importance because it completes an explanation for central near-location errors in the partial-report bar-probe task. The second purpose of the present study was to provide an explanation for these central shifts. For this explanation information about the exact size of the central shift is required. In Exps. 2, 3, and 4, with cursor setting as the task, it was attempted to assess more precisely the size of the central shifts. These experiments revealed that two different factors determine the results in cursor setting tasks; a factor "target position" and a factor "cursor position." Experiment 5 showed that it is the point of fixation, not the fixation point, that serves, at least in part, as the reference point in this type of task. All the findings together allow us to conclude that the target positions are underestimated by about 10%. From vision research it is known that saccadic eye movements, performed for bringing a target in the fovea, also show an undershoot of about 10%. It is therefore concluded that the system in charge of saccadic eye movements also provides the metric in visual space within a single eye fixation.
Abstract: When subjects are asked to determine where a fast-moving stimulus enters a window, they typically do not localize the stimulus at the edge, but at some later position within that window (Fröhlich effect). We report five experiments that explored this illusion. An attentional account is tested, assuming that the entrance of the stimulus in the window initiates a focus shift toward it. While this shift is under way, the stimulus moves into the window. Because the first phenomenal (i.e., explicitly reportable) representation of the stimulus will not be available before the end of the focus shift, the stimulus is perceived at some later position. In Experiment 1, we established the Fröhlich effect and showed that it size depends on stimulus parameters such as movement speed and movement direction. In Experiments 2 and 3, we examined the influence of eye movements and tested whether the effect changed when the stimuli were presented within a structural background or when they started from different eccentricities. In Experiments 4 and 5, specific predictions from the attentional model were tested: In Experiment 4 we showed that the processing of the moving stimulus benefits from a preceding peripheral cue indicating the starting position of the subsequent movement, which induces a preliminary focus shift to the position where the moving stimulus would appear. As a consequence the Fröhlich effect was reduced. Using a detection task in Experiment 5, we showed that feature information about the moving stimulus is lost when it falls into the critical interval of the attention shift. In conclusion, the present attentional account shows that selection mechanisms are not exclusively space based; rather, they can establish a spatial representation that is also used for perceptual judgement--that is, selection mechanisms can be space establishing as well.
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: Control panels of computer and other modern instruments are often equipped with so-called mode keys, the pressing of which changes the function of other control elements. Thus user keys have different functions depending on the current mode of the instrument. The question is, however, whether it is more userfriendly to have a panel with parallel arranged keys for each function (thus with almost direct possibility to intervene), or to have serial equipment with only a few user keys, where the different functions are only available if the user calls up the relevant machine mode (e.g. displayed on a monitor that operates with different switchable screens). In this case there exist only serial access possibilities. Two experiments compared performances with three types of user interfaces with and without mode keys on the basis of selection times and errors. Although mode keys apparently reduce the complexity of the user interface, our results show that they lead to slower and more often incorrect usage. However, the amount of practice was a moderator variable. As a consequence, for occasional users it is worth considering a less complex interface, that is, with mode keys, but for expert users an interface where each function has its own key should be preferred.
Abstract: Experimental designs that require the simultaneous perception and reproduction of a stimulus sequence could help to clarify the relationship between perception and action. This contribution examines a specific stimulus-response compatibility with the reproduction of simple stimulus sequences. In the procedure a response just prepared or one to be prepared is confronted with a new incoming stimulus that is compatible or incompatible with the response. Interference is predicted from a framework in which stimulus perception and action control are assumed to share common codes. Five arrows were successively presented at 1-s intervals. The arrows pointed either to the left or to the right with equal probability. One of the five arrows was accompanied by a randomly presented go signal. Subjects then had to reproduce the sequence by pressing corresponding left or right keys while the stimulus presentation continued. Reaction-time latencies and reaction intervals within a sequence were analyzed in six experiments. Results showed increasing reaction-time latencies the later the go signal was presented--that is, the longer the sequence to be reproduced was. In contrast to previous findings, this effect interacted with the compatibility between the arrow displayed together with the go signal and the first reaction. It is argued that the go signal initiates a transfer of a cognitive action plan to a peripheral motor program and that this process is subject to interference the more the current stimulus is at odds with one of the first parameter specification.
Abstract: Experimental designs that require the simultaneous perception and reproduction of a stimulus sequence could help to clarify the relationship between perception and action. This contribution examines a specific stimulus-response compatibility with the reproduction of simple stimulus sequences. In the procedure a response just prepared or one to be prepared is confronted with a new incoming stimulus that is compatible or incompatible with the response. Interference is predicted from a framework in which stimulus perception and action control are assumed to share common codes. Five arrows were successively presented at 1-s intervals. The arrows pointed either to the left or to the right with equal probability. One of the five arrows was accompanied by a randomly presented go signal. Subjects then had to reproduce the sequence by pressing corresponding left or right keys while the stimulus presentation continued. Reaction-time latencies and reaction intervals within a sequence were analyzed in six experiments. Results showed increasing reaction-time latencies the later the go signal was presented - that is; the longer the sequence to be reproduced was. In contrast to previous findings, this effect interacted with the compatibility between the arrow displayed together with the go signal and the first reaction. It is argued that the go signal initiates a transfer of a cognitive action plan to a peripheral motor program and that this process is subject to interference the more the current stimulus is at odds with one of the first para meter specification.
Abstract: Selection times of drop-down menus are in many ways influenced by cognitive and motor processes of the user and by design variables of the menu. Since the number of these variables is too large, the contribution of individual variables to selection time cannot be assessed by using factorial designs. Multiple regression is introduced to solve this problem. The technique uses selection times as criterions and a set of general menu characteristics as predictors. The non-standardized slopes beta report the increase (or decrease) in selection time which can be assessed for each predictor. In a first experiment, the validity of the technique was demonstrated replicating various well-known effects in a mouse-driven editor. For example, the selection times increased with the number of subordinate menu items or atypical items. Further, due to motor components of the mouse movement, selection times depended on the spatial position of an item within the menu. In a second experiment, mouse selection was replaced by key selection to stress cognitive processes contributing to response times. The technique yielded results that were sensitive to this variation. Limitations of the technique are discussed.
Abstract: One implication of the spotlight metaphor of visual-attention shifts is that attention moves from position to position, from one object in the visual field to another. According to this view, attention shifts start at the last-focussed position, their spatiotemporal course therefore being position dependent. A different, yet also position-dependent, formulation is implied in the so-called "premotor hypothesis of attention" (Rizzolatti et al., 1987; Umiltà et al., 1991). In this paper these two accounts are tested against an alternative, position-independent conception. It is maintained that in the case of onset-triggered processes, the course of the attentional shifts is independent of the last-focussed position. On the basis of these considerations, three experiments measure choice-reaction times of stimuli at different spatial positions after peripheral cuing of the same or another position within the visual field. Results show no evidence for the position-dependent conception of the spotlight metaphor or the premotor hypothesis with a long SOA (stimulus-onset asynchrony) between cue and stimulus. Only with a short SOA is the premotor hypothesis supported by the data. As an alternative interpretation, a position-independent thesis is favored, in which it is assumed that attention shifts can be adjusted during an early stage of processing.
Abstract: When two vertical rods move through a horizontal window in close succession, the Tandem Effect can be observed. It consists of a spatial illusion (distance between the rods looking smaller than it actually is) and a temporal illusion (under certain conditions both rods are seen simultaneously in the window, though the first rod has left the window before the second rod enters it). We report six experiments that explored the distance-reduction illusion and tested an attentional model of the effect. It assumes that attention is initially focused on the first rod and then shifted to the second, when it enters the window. The percept of the pair of rods is integrated from the first rod's position at the beginning, and the second rod's position at the end, of the focus shift. Consequently their subjective distance will be smaller than their physical distance by the distance that they travel during the focus shift. Experiments 1 and 2 established the Tandem Effect as an empirical phenomenon and showed that its size depends on stimulus parameters such as window size and movement speed. Experiments 3-5 tested specific predictions from the attentional model. Experiment 6 examined a further illusion, the Fröhlich Effect, and showed that it can be subsumed under the model. The experiments produced some unexpected effects and some predictions from the model were only partly confirmed. It is shown that the main findings can be combined into two quantitative functions that describe the course of focusing. One implication is that visual attention does not "move" from one object to another; rather all attention shifts originate in the fovea. We discuss several alternative interpretations of our data and show that they are less satisfactory than the attentional model.
Abstract: It is examined whether and how the perspective of seeing oneâs own movements exerted an influence on action control. Such change in the perspective challenges an information processor, as she or he has to handle successfully the discrepancies between the tactile/proprioceptive feedback and the visual feedback on a projection screen. In the experiments participants responded to visual stimuli, but saw their responses either from the top or with an x-axis reflection, a y-axis reflection, or a reflection about both axes. The results showed that a change in perspective did not impair performance as long as the leftâright relations corresponded with the body space (e.g., with visual feedback reflected about the x-axis). By contrast, performance was drastically reduced when visual feedback was reflected about the y-axis or about both axes, so that performed left-side (right-side) movements were seen as right-side (left-side) movements. It is concluded that an actor preferably relies on the information of the visual system, but refers to the tactile/proprioceptive information when it facilitates the task demands.
