The reviewing of object files: object-specific integration of information.

A series of experiments explored a form of object-specific priming. In all experiments a preview field containing two or more letters is followed by a target letter that is to be named. The displays are designed to produce a perceptual interpretation of the target as a new state of an object that previously contained one of the primes. The link is produced in different experiments by a shared location, by a shared relative position in a moving pattern, or by successive appearance in the same moving frame. An object-specific advantage is consistently observed: naming is facilitated by a preview of the target, if (and in some cases only if) the two appearances are linked to the same object. The amount and the object specificity of the preview benefit are not affected by extending the preview duration to 1 s, or by extending the temporal gap between fields to 590 ms. The results are interpreted in terms of a reviewing process, which is triggered by the appearance of the target and retrieves just one of the previewed items. In the absence of an object link, the reviewing item is selected at random. We develop the concept of an object file as a temporary episodic representation, within which successive states of an object are linked and integrated.     

The effects of spatial stimulus-response compatibility on choice time production accuracy and variability

Five experiments examined the relations between timing and attention using a choice time production task in which the latency of a spatial choice response is matched to a target interval (3 or 5 s). Experiments 1 and 2 indicated that spatial stimulus-response incompatibility increased nonscalar timing variability without affecting timing accuracy and that choice reaction time practice reduced choice time production variability. These data support a "temporal discounting" model in which response choice and timing occur in series, but the interval timed is shortened to account for nontemporal processing. In Experiment 3, feedback and anticipation task demands improved choice time production accuracy. In Experiments 4 and 5, the delay between the start-timing and choice-decision signals interacted with choice difficulty to affect choice time production accuracy and variability when timing a 3- but not a 5-s interval, suggesting that attention mediates timing before and after an interruption in timing.     

Differential dynamics of spatial and non-spatial stimulus-response compatibility effects: a dual task LRP study

Choice reaction times are shorter when stimulus and response features are compatible rather than incompatible. Recent studies revealed that spatial compatibility effects in Simon tasks are strongly attenuated when there is temporal overlap with a different high-priority task. In contrast, non-spatial variants of the Simon task appear to be unaffected by task overlap. The present study used the lateralized readiness potential (LRP) within a dual task design to elucidate the dynamics underlying these differential effects for a color and a spatial variant of the Simon task. In the color version there was no sign of early response priming by irrelevant stimulus features in the LRP. The color compatibility effect was independent of task overlap and reflected in the LRP onset latency. In contrast, in the spatial version, priming by irrelevant stimulus location showed up and was mirrored by early LRP activation. Response priming and the corresponding Simon effect, however, were present only in case of little temporal overlap with the primary task. The absence of spatial compatibility effects at strong temporal overlap suggests that response conflicts due to stimulus-related priming depend on the availability of processing resources.     

Sequence learning in Parkinson's disease: the effect of spatial stimulus-response compatibility

Patients with Parkinson's disease (PD) have repeatedly demonstrated reduced sequence-specific learning effects in serial reaction time tasks (SRTs). Previous research with PD patients has mainly employed the 'classical' SRT task, involving a spatially compatible assignment of stimuli and responses. From cognitive research, it is known that spatial compatibility triggers rapid, automatic responses in the direction of the stimulus. Automatic responding has shown to be disinhibited in PD patients and may therefore interfere with stimulus anticipation during the learning process. The aim of the present study was to test this hypothesis by investigating if reduced sequence-specific learning depends on spatial stimulus-response compatibility. PD patients and age-matched controls were examined either with an SRT variant involving central stimulus presentation, thereby preventing automatic linking of stimulus and response locations, or with a spatially compatible SRT task. Patients showed reduced sequence-specific learning effects only when the stimulus-response assignment was spatially compatible. This pattern of results confirms the hypothesis that sequence learning deficits in PD may result from a predominance of automatic response activation over learning-based stimulus anticipations during the learning phase.     

Effects of multiple reference points in spatial stimulus-response compatibility.

In two experiments, spatial stimulus-response compatibility effects in situations where the stimulus could appear in eight different locations were investigated. The locations were obtained as a result of orthogonal manipulation of hemispace, visual hemifield within hemispace, and relative position within hemifield. In the first experiment, only relative position within hemifield was relevant for selecting one of two responses (left or right). The results showed that both hemifield and relative position formed the basis of compatibility effects. In the second experiment, which was in most respects identical to the first, all spatial information was irrelevant. Only the geometrical shape of the stimulus determined the correct response. The results showed three S-R compatibility effects, based on hemispace, hemifield, and relative position. These results contradict earlier findings, and have implications for models of stimulus-response compatibility.     

Persistence of stimulus-response compatibility effects with extended practice.

The influence of extended practice on stimulus-response (S-R) compatibility effects was investigated. Three experiments, each extending over a period of 8 sessions, were conducted. The nature and degree of compatibility was manipulated across experiments. In all experiments, a persistent effect of S-R compatibility on reaction times was observed. Thus, the lower bound for reaction times appears to be less for compatible assignments than for incompatible assignments. This persistence of S-R compatibility indicates that the initial codings used to perform a novel task continue to exert an influence on later performance.     

Influences of multiple spatial stimulus and response codes on orthogonal stimulus-response compatibility

When up-down stimuli are mapped to left-right responses, an up-right/down-left mapping advantage is found that is modified by response eccentricity and hand posture. These effects can be attributed to correspondence of asymmetric stimulus and response codes formed relative to multiple reference frames. We examined the influence of stimulus-set location on these orthogonal stimulus-response compatibility (SRC) effects. In Experiment 1, the stimulus set appeared in the upper or lower display positions. A spatial code for stimulus-set location was formed, producing Simon-type response eccentricity and hand posture effects, but this code had no influence on the coding of the relevant stimuli. In Experiment 2, the stimulus set appeared in the left, center, or right positions relative to the response location, which also varied, to dissociate the effects of response location, relative to the stimulus display and body midline. The former factor influenced the orthogonal SRC effect for both unimanual switch movements and bimanual keypresses, and the latter factor influenced the effect for only unimanual switch movements. Stimulus-set location causes orthogonal Simon-type effects when varied along the stimulus dimension and provides a referent for response coding when varied along the response dimension.     

Reducing and restoring stimulus-response compatibility effects by decreasing the discriminability of location words

In two experiments, we compared level of activation and temporal overlap accounts of compatibility effects in the Simon task by reducing the discriminability of spatial and non-spatial features of a target location word. Participants made keypress responses to the non-spatial or spatial feature of centrally presented location words. The discriminability of the spatial feature of the word (Experiment 1), or of both the spatial and non-spatial feature (Experiment 2), was manipulated. When the spatial feature of the word was task-irrelevant, lowering the discriminability of this feature reduced the compatibility effect. The compatibility effect was restored when the discriminability of both the task-relevant and task-irrelevant features were reduced together. Results provide further evidence for the temporal overlap account of compatibility effects. Furthermore, compatibility effects when the spatial information was task-relevant and those when the spatial information was task-irrelevant were moderately correlated with each other, suggesting a common underlying mechanism in both versions.     

Attention to object files defined by transparent motion

Two interspersed and differently colored sets of dots were rotated in opposite directions and were perceived as superimposed transparent surfaces. Probes consisting of brief changes in dot motion direction were reported. Two probes affecting the same surface were discriminated accurately. The 2nd probe was discriminated poorly if it affected a surface different from the 1st and if the time between probes was less than 600 ms. This reflects a difficulty in switching attention rapidly between surfaces. Spatial proximity increased the interference. Controls were incompatible with traditional spatial mechanisms (2- or 3-dimensional) or with simple sensory filters. Instead, probes were apparently selected by object files. The interference is not simply due to an inability to process 2 objects at once but requires close spatial proximity of incompatible motion signals.     

Bayesian integration of spatial information

Spatial judgments and actions are often based on multiple cues. The authors review a multitude of phenomena on the integration of spatial cues in diverse species to consider how nearly optimally animals combine the cues. Under the banner of Bayesian perception, cues are sometimes combined and weighted in a near optimal fashion. In other instances when cues are combined, how optimal the integration is might be unclear. Only 1 cue may be relied on, or cues may seem to compete with one another. The authors attempt to bring some order to the diversity by taking into account the subjective discrepancy in the dictates of multiple cues. When cues are too discrepant, it may be best to rely on 1 cue source. When cues are not too discrepant, it may be advantageous to combine cues. Such a dual principle provides an extended Bayesian framework for understanding the functional reasons for the integration of spatial cues.     

Effects of visual cue and response assignment on spatial stimulus coding in stimulus-response compatibility

Tlauka and McKenna ( 2000 ) reported a reversal of the traditional stimulus-response compatibility (SRC) effect (faster responding to a stimulus presented on the same side than to one on the opposite side) when the stimulus appearing on one side of a display is a member of a superordinate unit that is largely on the opposite side. We investigated the effects of a visual cue that explicitly shows a superordinate unit, and of assignment of multiple stimuli within each superordinate unit to one response, on the SRC effect based on superordinate unit position. Three experiments revealed that stimulus-response assignment is critical, while the visual cue plays a minor role, in eliciting the SRC effect based on the superordinate unit position. Findings suggest bidirectional interaction between perception and action and simultaneous spatial stimulus coding according to multiple frames of reference, with contribution of each coding to the SRC effect flexibly varying with task situations.     

S-R compatibility effects due to context-dependent spatial stimulus coding

Responses are faster with spatial S-R correspondence than with noncorrespondence (spatial compatibility effect), even if stimulus location is irrelevant (Simon effect). In two experiments, we sought to determine whether stimuli located above and below a fixation point are coded as left and right (and thus affect the selection of left and right responses) if the visual context suggests such a coding. So, stimuli appeared on the left or right eye of a face’s image that was tilted by 90° to one side or the other (Experiment 1) or varied between upright and 45° or 90° tilting (Experiment 2). Whether stimulus location was relevant (Experiment 1) or not (Experiment 2), responses were faster with correspondence of (face-based) stimulus location and (egocentrically defined) response location, even if stimulus and response locations varied on physically orthogonal dimensions. This suggests that object-based spatial stimulus codes are formed automatically and thus influence the speed of response selection.     

Effects of spatial compatibility on integration processes in graph comprehension

A precondition for efficiently understanding and memorizing graphs is the integration of all relevant graph elements and their meaning. In the present study, we analyzed integration processes by manipulating the spatial compatibility between elements in the data region and the legend. In Experiment 1, participants judged whether bar graphs depicting either statistical main effects or interactions correspond to previously presented statements. In Experiments 2 and 3, the same was tested with line graphs of varying complexity. In Experiment 4, participants memorized line graphs for a subsequent validation task. Throughout the experiments, eye movements were recorded. The results indicated that data-legend compatibility reduced the time needed to understand graphs, as well as the time needed to retrieve relevant graph information from memory. These advantages went hand in hand with a decrease of gaze transitions between the data region and the legend, indicating that data-legend compatibility decreases the difficulty of integration processes.     

Representing response position relative to display location: Influence on orthogonal stimulus-response compatibility

Two types of stimulus-response compatibility (SRC) effect occur with orthogonal stimulus and response sets, an overall up-right/down-left advantage and mapping preferences that vary with response position. Researchers agree that the former type is due to asymmetric coding of the stimulus and response alternatives, but disagree as to whether the latter type requires a different explanation in terms of the properties of the motor system. This issue is examined in three experiments. The location of the stimulus set influenced orthogonal SRC when it varied along the same dimension as the responses (Experiments 1 and 2), with the pattern predicted by the hypothesis that the stimulus set provides a referent relative to which response position is coded. The effect of stimulus-set location on orthogonal SRC was independent of the stimulus onset asynchrony (SOA) for a marker that indicated stimulus-set side and the imperative stimulus. In contrast, a spatial correspondence effect for the irrelevant stimulus-set location and response was a decreasing function of SOA. Experiment 3 showed that the orthogonal SRC effect was determined by response position relative to the stimulus-set location and not the body midline. The results support the view that both types of orthogonal SRC effects are due to asymmetric coding of the stimuli and responses.     

Infants' knowledge of objects: beyond object files and object tracking

Two independent research communities have produced large bodies of data concerning object representations: the community concerned with the infant's object concept and the community concerned with adult object-based attention. We marshal evidence in support of the hypothesis that both communities have been studying the same natural kind. The discovery that the object representations of young infants are the same as the object files of mid-level visual cognition has implications for both fields.     

Musical notation for the keyboard: An examination of stimulus-response compatibility

A recent stimulus-response compatibility model was used to provide a performance evaluation of an experimental notation for the keyboard in which pitch varies horizontally in visual space. One hundred and twenty subjects performed a choice reaction time task using either the horizontal notation or a more traditional vertical notation. Half the subjects in each notation group received white noise and half received pitch-varying feedback with responses. A horizontal display advantage was revealed when rules of the model were applied to data analyses. Further, the horizontal display advantage was not dependent on the nature of the feedback. In a second experiment, performance of musicians and non-musicians was compared using the horizontal and vertical notations. Musicians' performance was uniformly better than that of non-musicians, and did not differ with notation orientation. The findings support the use of non-traditional horizontal notations for novice performance on a keyboard instrument.     

Vision-for-action: The effects of object property discrimination and action state on affordance compatibility effects

When a person views an object, the action the object evokes appears to be activated independently of the person’s intention to act. We demonstrate two further properties of this vision-to-action process. First, it is not completely automatic, but is determined by the stimulus properties of the object that are attended. Thus, when a person discriminates the shape of an object, action affordance effects are observed; but when a person discriminates an object’s color, no affordance effects are observed. The former, shape property is associated with action, such as how an object might be grasped; the latter, color property is irrelevant to action. Second, we also show that the action state of an object influences evoked action. Thus, active objects, with which current action is implied, produce larger affordance effects than passive objects, with which no action is implied. We suggest that the active object activates action simulation processes similar to those proposed in mirror systems.     

The integration of spatial information across different viewpoints

The integration of spatial information perceived from different viewpoints is a frequent, yet largely unexplored, cognitive ability. In two experiments, participants saw two presentations, each consisting of three targets—that is, illuminated tiles on the floor—before walking the shortest possible path across all targets. In Experiment 1, participants viewed the targets either from the same viewpoint or from different viewpoints. Errors in recalling targets increased if participants changed their viewpoints between presentations, suggesting that memory acquired from different viewpoints had to be aligned for integration. Furthermore, the error pattern indicates that memory for the first presentation was transformed into the reference frame of the second presentation. In Experiment 2, we examined whether this transformation occurred because new information was integrated already during encoding or because memorized information was integrated when required. Results suggest that the latter is the case. This might serve as a strategy for avoiding additional alignments.     

Automatic spatial coding of perceived gaze direction is revealed by the Simon effect

In a typical Simon task, the (irrelevant) spatial position of the stimulus interferes with the processing of the salient characteristic (e.g., color). We used the Simon effect to investigate the automatic processing of gaze cues. We show that a simple drawing of schematic eyes automatically generates a spatially defined code of gaze direction. Although completely irrelevant to the task, direction of gaze influenced reaction times in a spatially selective two-choice discrimination based on eye color. Moreover, in one experiment employing an orthogonal manipulation of stimulus position and gaze direction, we found that coding of gaze direction is independent of stimulus spatial coding. Our finding of a “gazedirection Simon effect” is congruent with the hypothesis that gaze direction is coded by a specialized mechanism.     

Increased spatial salience in the social Simon task: A response-coding account of spatial compatibility effects

A spatial compatibility effect (SCE) is typically observed in forced two-choice tasks in which a spatially defined response (e.g., pressing a left vs. a right key) has to be executed to a nonspatial feature of a stimulus (e.g., discriminating red from green) that is additionally connoted by a spatial feature (e.g., the stimulus points to the left or the right). Responses are faster and more accurate when the response side and the spatial stimulus feature are compatible than when they are incompatible. Previous research has demonstrated that SCEs are diminished when stimuli from only one response category are responded to in individual go/no-go tasks, whereas SCEs reemerge when two participants work jointly on two complementary, individual go/no-go tasks in a joint go/no-go task setting. This social Simon effect has been considered evidence for shared task representations. We show that SCEs emerge in individual go/no-go tasks when the spatial dimension is made more salient, whereas SCEs are eliminated in joint go/no-go tasks when the spatial dimension is made less salient. These findings are consistent with an account of social Simon effects in terms of spatial response coding, whereas they are inconsistent with an account of shared task representations. The relevance of social factors for spatial response coding is discussed.