Inhibition of return and manual pointing movements

To examine whether the motor inhibition of return (IOR) postulated by Taylor and Klein (1998, 2000) generalizes to manual guided movements or is restricted to saccadic responses, the following three experiments were conducted. The first experiment combined peripheral cues (which generate IOR) with four types of manual responses made to central targets (central arrow indicating the response location). The responses were made on a touch-screen and were the equivalent of either a detection keypress, a choice keypress, a detection-guided pointing movement, or a choice-guided pointing movement. No IOR was found for any of the responses. The second experiment replicated the main result under eye fixation control. In Experiment 3, peripheral cues and peripheral targets were used, and IOR was present in all responses. Overall, these finding suggest that motor-based IOR is restricted to the oculomotor system. Implications for motor-based IOR and attention-based IOR are discussed.     

Inhibition of return in manual and saccadic response systems

When nonpredictive exogenous visual cues are used to reflexively orient covert visual spatial attention, the initial early facilitation for detecting stimuli at cued versus uncued spatial locations develops into inhibition by 300 msec following the cue, a pattern referred to as inhibition of return (IOR). Experiments were carried out comparing the magnitude and time course for development of IOR effects when manual versus saccadic responses were required. The results showed that both manual and saccadic responses result in equivalent amounts of facilitation following initial exposure to a spatial cue. However, IOR developed more quickly for saccadic responses, such that, at certain cue-target SOAs, saccadic responses to targets were inhibited, whereas manual responses were still facilitated. The findings are interpreted in terms of a premotor theory of visual attention.     

Inhibition of return in discrimination tasks

Although inhibition of return is known to affect a wide range of detection tasks, it has not been found consistently in discrimination tasks. To examine this issue, 5 experiments were conducted in which participants discriminated between a visual target and a distractor. The responses were not inhibited if, before the onset of stimuli, attention had been overtly oriented (i.e., an eye movement was made) to the future target location and the stimulus at that location was the same symbol as the upcoming target. However, if attention was covertly oriented (i.e., no eye movement was made) to the future location of the target, or if the stimulus at the earlier attended location was a symbol different from the target, responses to the target were inhibited. Overall, the findings provide insights into the relation between movements of attention and discrimination judgments and support the notion that inhibition of return is an attentional phenomenon.     

Inhibition of return in location- and identity-based choice decision tasks

Three experiments were conducted to determine whether inhibition of return can be best characterized as an attentional or a motor phenomenon. In the first experiment, subjects made choice key-press responses to the location of a target (left or right) or the identity of the target (X or +) by pressing a left or right response key. In the second experiment, the display was rotated 90° so that there was no direct spatial mapping between the vertically aligned stimulus display and the horizontally aligned response keys. In both experiments, inhibition of return was observed for location-based and identity-based choice responses, although more inhibition was seen in the identity-based responses. The results of the third experiment suggested that this larger inhibitory effect may be specific to the covert orienting of reflexive attention in response to the sudden appearance of a single peripheral stimulus in the identity tasks. Overall, the results are consistent with the attentional, not the motor, explanation of inhibition of return.     

Strategies of flanker coprocessing in single and dual tasks

In this study, the authors used a dual-task flanker paradigm to investigate the degree to which flankers are coprocessed with the target as a function of whether flankers have to be used as stimuli for a second task. A series of experiments, in which performance in dual tasks was compared with that in single tasks, revealed that participants had a strong tendency to coprocess flankers to a large degree in dual tasks, even if this impaired performance. Coprocessing of flankers was reduced only when totally irrelevant flankers were presented at the beginning of a trial or single tasks were performed on the great majority of trials within a block. The results suggest that it was demanding to process targets and flankers serially when both had to be used for a dual task. As a consequence, target and flankers were processed in parallel, even if this was nonoptimal for target selection.     

Inhibition of return and repetition priming effects in localization and discrimination tasks.

Inhibition of return (IOR) refers to slower responding to a stimulus that is presented at the same, rather than a different location as a preceding, spatially nonpredictive, stimulus. Repetition priming refers to speeded responding to a stimulus that duplicates the visual characteristics of a stimulus that precedes it. IOR and repetition priming effects interact in nonspatial discrimination tasks but not in localization tasks; three experiments examined whether this is due to processing differences or due to response differences between tasks. Two stimuli, S1 and S2, occurred on each trial. In Experiment 1, S1 and S2 were both peripheral arrows; in Experiment 2, S1 was a central arrow and S2 was a peripheral nondirectional rectangle; in Experiment 3, S1 was a peripheral nondirectional rectangle and S2 was a peripheral arrow. S1 never required a response; S2 required a localization or a discrimination response. Despite evidence that form information was likely extracted from the arrow stimuli, the localization task revealed no repetition priming: IOR occurred regardless of shared visual identity of the S1 and S2 arrows. The discrimination task revealed IOR only when the visual identity changed from S1 to S2; otherwise, facilitation occurred. These results suggest that IOR is masked by repetition priming only when the response depends on the explicit processing of form information; repetition priming does not occur when such information is extracted automatically but is task (and response) irrelevant.     

Effects of spatial response coding on distractor processing: Evidence from auditory spatial negative priming tasks with keypress,joystick, and head movement responses

Attention, Perception, & Psychophysics - Prior studies of spatial negative priming indicate that distractor-assigned keypress responses are inhibited as part of visual, but not auditory,...     

Distinct mechanisms for planning keypress and reaching responses: a developmental study

This study examined developmental effects in the ability to use precue information for the planning of keypress and reaching responses. Participants from four age groups (7, 9, 13, and 21 year olds) performed a spatial precuing task either by pressing one of four response keys (keypress task) or by reaching directly toward one of the four target locations on the screen (reaching task). Reaction time data revealed striking age differences in the ability to use advance information in the keypress task, not in the reaching task. This dissociation confirms the hypothesis that distinct and separate mechanisms govern the planning of indirect keypress and direct reaching responses.     

Inhibition of return promotes stop-signal inhibition by delaying responses

Inhibition of return (10R) refers to a mechanism that slows response times (RTs) to detect, localize, or discriminate a target that is presented at a location previously occupied by an irrelevant peripheral cue. Generally, the slowing of RTs is described as a negative effect on responding that is believed to promote searching to new locations. In this report, we consider whether IOR might benefit performance when the goal is to prevent a prepared response. Using the stop-signal paradigm, we show that IOR improved the ability to inhibit a prepared response by delaying responses to the target. Thus, in addition to aiding visual search, IOR may also provide an opportunity for the adjustment of decisions and behaviour in accordance with the demands of a dynamic environment.     

The development of children's knowledge of attention and resource allocation in single and dual tasks

Developmental changes in kindergarten, 1st-, and 4th-grade children's knowledge about the variables that affect attention sharing and resource allocation were examined. Findings from the 2 experiments showed that kindergartners understood that person and strategy variables affect performance in attention-sharing tasks. However, knowledge of how task variables affect performance was not evident to them and was inconsistent for 1st and 4th graders. Children's knowledge about resource allocation revealed a different pattern and varied according to the dissimilarity of task demands in the attention-sharing task. In Experiment 1, in which the dual attention tasks were similar (i.e., visual detection), kindergarten and 1st-grade children did not differentiate performance in single and dual tasks. Fourth graders demonstrated knowledge that performance on a single task would be better than performance on the dual tasks for only 2 of the variables examined. In Experiment 2, in which the dual attention tasks were dissimilar (i.e., visual and auditory detection), kindergarten and 1st-grade children demonstrated knowledge that performance in the single task would be better than in the dual tasks for 1 of the task variables examined. However, 4th-grade children consistently gave higher ratings for performance on the single than on the dual attention tasks for all variables examined. These findings (a) underscore that children's meta-attention is not unitary and (b) demonstrate that children's knowledge about variables affecting attention sharing and resource allocation have different developmental pathways. Results show that knowledge about attention sharing and about the factors that influence the control of attention develops slowly and undergoes reorganization in middle childhood.     

Structured perceptual arrays and the modulation of Fitts's law: examining saccadic eye movements

On the basis of recent observations of a modulation of Fitts's law for manual pointing movements in structured visual arrays (J. J. Adam, R. Mol, J. Pratt, & M. H. Fischer, 2006; J. Pratt, J. J. Adam, & M. H. Fischer, 2007), the authors examined whether a similar modulation occurs for saccadic eye movements. Healthy participants (N = 19) made horizontal saccades to targets that appeared randomly in 1 of 4 positions, either on an empty background or within 1 of 4 placeholder boxes. Whereas in previous studies, placeholders caused a decrease in movement time (MT) without the normal decrease in movement accuracy predicted by Fitts's law, placeholders in the present experiment increased saccadic accuracy (decreased endpoint variability) without an increase in MT. The present results extend the findings of J. J. Adam et al. of a modulation of Fitts's law from the temporal domain to the spatial domain and from manual movements to eye movements.     

The tell-tale tasks: a review of saccadic research in psychiatric patient populations

This review focuses on saccade research with adult psychiatric patients. It begins with an introduction of the various types of saccades and the tasks used to evoke them. The functional significance of the different types of eye movements is briefly discussed. Research findings regarding the saccadic performance of different adult psychiatric patient populations are discussed in detail, with particular emphasis on findings regarding error rates, response latencies, and any specific task parameters that might affect those variables. Findings regarding the symptom, neurocognitive, and neural correlates of saccadic performance and the functional significance of patients’ saccadic deficits are also discussed. We also discuss the saccadic deficits displayed by various patient groups in terms of circuitry (e.g. cortical/basal ganglia circuits) that may be implicated in the underlying pathophysiology of several of these disorders. Future directions for research in this growing area are offered.     

Inhibition of return: Unraveling a paradox

Although inhibition of return (IOR) is widely believed to aid search by discouraging reexamination of previously inspected locations, its impact actually appears to decline as the number of target locations increases. We test three possible reasons for this paradoxical result: (1) IOR is capacity-limited, (2) IOR is sensitive to subtle changes in target location probability, and (3) IOR decays with distance from a previously attended location. The present investigation provides strong support for the third explanation, indicating that a gradient of inhibition is centered on previously attended locations. We note that this inhibitory gradient resolves a paradox in the literature. Moreover, we speculate that the inhibitory gradient may reflect a “similarity space” within which target locations near to the cue are tagged with inhibition due to their similarity to the cued location. The farther the target location is away, the less similar it is to the cued location, and thus the less inhibition it receives.     

Inhibition of return in perception and action

Inhibition of return (IOR) refers to the delay in responses to previously cued locations. Whether IOR influences perceptual and/or motor processes has been controversial. To determine IOR effects on perception and action, this study examined IOR in spatially directed hand reaching (Experiment 1) and spatial localization of targets with a mouse cursor (i.e., an indirect visuomotor mapping/perceptual task; Experiment 2). The reaction times showed delayed responses for targets appearing within the whole cued hemifield for both tasks. However, hypometric spatial biases were consistently found only with directed reaching. Spatial biases in the mouse localization task were indirectly influenced by IOR and distinct from those in the reaching task. The dissociation in spatial characteristics for directed reaching vs. perception suggests that the effects of IOR are task dependent, but may be more directly linked to the dorsal motor system.     

Inhibition of return in children and adolescents

Inhibition of return (IOR), slowed responding to targets at a cued location after attention is removed from this location, has been shown to occur both in adults and in infants. To explore suggestion that the timecourse of IOR depends on factors that might affect the efficiency with which attention is removed from the cued location, we compared the performance of young children (5-10-year-olds, N=49, M=8 years, 4 months) to older children and adolescents (11-17-year-olds, N=61, M=14 years) in single and double cue procedures. Cue-target interval was varied to measure the timecourse of IOR in this within-subjects localization task. Whereas no IOR was found in the young group unless a double cue procedure was used, in the older group, we found IOR at all intervals with the double cue procedure and the typical crossover pattern, with early facilitation followed by inhibition in the single cue procedure.     

Object-based correspondence effects for action-relevant and surface-property judgments with keypress responses: evidence for a basis in spatial coding

It has been proposed that grasping affordances produce a Simon-type correspondence effect for left–right keypress responses and the location of the graspable part of an object for judgments based on action-relevant properties such as shape, but not on surface properties. We tested the implications of this grasping affordance account and contrasted them with the ones derived from a spatial coding account that distinguishes holistic processing of integral dimensions and analytic processing of separable dimensions. In Experiments 1–3, judgments about the color of a door handle showed a Simon effect relative to the handle’s base, whereas judgments about the handle’s shape showed no Simon effect. In Experiment 4, when the middle of the handle was colored, the Simon effect was obtained relative to the base, but when the color was at the tip of the handle or near the base, Simon effects were obtained relative to the color location. For Experiment 5, only the base was colored, and the Simon effect was larger for a passive rather than active handle state, as in the color-judgment conditions of Experiments 2–4 in which the colored region overlapped with the base. In Experiment 6, orientation judgments showed no Simon effect, as the shape judgments did in Experiments 1 and 2. The findings of (a) an absence of Simon effects for shape and orientation judgments, (b) no larger Simon effects for active than passive handle states, and (c) isolation of the changing component for color judgments are consistent with the spatial coding account, according to which the distinction between object shape/orientation and color is one of integral versus separable dimensions.     

Arithmetic operation and working memory: differential suppression in dual tasks

The relationship between arithmetic function and working memory was examined using a dual-task paradigm for either phonological or visuo-spatial suppression. Simultaneous phonological rehearsal significantly delayed the performance of multiplication but not subtraction, whereas holding an image in the mind delayed subtraction but not multiplication. This result indicates that arithmetic function is related to working memory in a subsystem-specific manner: multiplication is more closely linked to phonological loop and subtraction to visuo-spatial sketchpad. Whereas this is not compatible with the notion that arithmetic is done on a unitary, amodal representation of numbers, it provides support for the triple-code and/or the modular processing models on human numerical cognition in which number representations are specific for input/output modality and arithmetic types.     

Response preparation and code overlap in dual tasks

In a dual-task paradigm, a visual-encoding task with a deferred verbal report of a moving target was combined with a speeded task, in which participants prepared a precued leftward or rightward key-press response that was withheld until an auditory go signal. We manipulated the interval between the response cue and the target for the visual-encoding task, the interval between this target and the go signal, and spatial cross-task compatibility between the direction of the target movement in the visual task and the speeded manual response. The results of two experiments suggest that visual encoding interferes with response preparation and with the initiation of the prepared manual response at a short target-go interval. Also, responses were faster in compatible than in incompatible trials, indicating a cross-task compatibility effect. Experiment 2 reversed this compatibility effect by instruction, suggesting that the compatibility effect is based on response-response overlap. In both experiments, response preparation impaired accuracy in the visual task. Taken together, these results suggest that response processes and visual encoding share common codes and processes.     

Task-set inertia and memory-consolidation bottleneck in dual tasks

Three dual-task experiments examined the influence of processing a briefly presented visual object for deferred verbal report on performance in an unrelated auditory-manual reaction time (RT) task. RT was increased at short stimulus-onset asynchronies (SOAs) relative to long SOAs, showing that memory consolidation processes can produce a functional processing bottleneck in dual-task performance. In addition, the experiments manipulated the spatial compatibility of the orientation of the visual object and the side of the speeded manual response. This cross-task compatibility produced relative RT benefits only when the instruction for the visual task emphasized overlap at the level of response codes across the task sets (Experiment 1). However, once the effective task set was in place, it continued to produce cross-task compatibility effects even in single-task situations (“ignore” trials in Experiment 2) and when instructions for the visual task did not explicitly require spatial coding of object orientation (Experiment 3). Taken together, the data suggest a considerable degree of task-set inertia in dual-task performance, which is also reinforced by finding costs of switching task sequences (e.g., AC → BC vs. BC → BC) in Experiment 3.     

Inhibition of return: Dissociating attentional and oculomotor components

Inhibition of return (IOR) describes a performance decrement for stimuli appearing at recently cued locations. Both attentional and motor processes have been implicated in the IOR effect. The present data reveal a double dissociation between the attentional and motor components of IOR whereby the motor-based component of IOR is present when the response is oculomotor, and the attention-based component of IOR is present when the response is manual. These 2 distinct components should be considered and studied separately, as well as in relation to each other, if a comprehensive theory of IOR is to be achieved. ((c) 2003 APA, all rights reserved)