Biomedical subjects

Alan Kingstone

Publications and source records attributed to Alan Kingstone.

At least 37 records · Page 2Linked to original sources

PubMed2005

On audiovisual spatial synergy: the fragility of the phenomenon.

Recent literature has highlighted the importance and ubiquity of cross-modal links in spatial attention, whereby shifts in attention in one modality often induce corresponding shifts in other modalities. We attempted to provide further evidence for the case of audiovisual links during sustained endogenous attention by addressing several potential methodological confounds in previous demonstrations. However, we failed repeatedly to reproduce the phenomenon of spatial synergies between auditory and visual attention, found by Driver and Spence (1994) and frequently cited to support the automatic nature of cross-modal attention links. We discuss the results in light of recent evidence about cross-modal spatial links during sustained attention and support the idea that such links can weaken or even disappear under certain circumstances, such as during periods of sustained attention. The implication is that individuals can select inputs from different modalities from different locations more easily than previously had been thought.

Adult↗

PubMed2005

Spatial orienting of tactile attention induced by social cues.

Several studies have established that humans orient their visual attention reflexively in response to social cues such as the direction of someone else's gaze. However, the consequences of this kind of orienting have been addressed only for the visual system. We investigated whether visual social attention cues can induce shifts in tactile attention by combining a central noninformative eye-gaze cue with tactile targets presented to participants' fingertips. Data from speeded detection, speeded discrimination, and signal detection tasks converged on the same conclusion: Eye-gaze-based orienting facilitates the processing of tactile targets at the location of the gazed-at body location. In addition, we examined the effects of other directional cues, such as conventional arrows, and found that they can be equally effective. This is the first demonstration that social attention cues have consequences that reach beyond their own sensory modality.

Attention↗

PubMed2004

Assessing automaticity in the audiovisual integration of motion.

This study examined the multisensory integration of visual and auditory motion information using a methodology designed to single out perceptual integration processes from post-perceptual influences. We assessed the threshold stimulus onset asynchrony (SOA) at which the relative directions (same vs. different) of simultaneously presented visual and auditory apparent motion streams could no longer be discriminated (Experiment 1). This threshold was higher than the upper threshold for direction discrimination (left vs. right) of each individual modality when presented in isolation (Experiment 2). The poorer performance observed in bimodal displays was interpreted as a consequence of automatic multisensory integration of motion information. Experiment 3 supported this interpretation by ruling out task differences as the explanation for the higher threshold in Experiment 1. Together these data provide empirical support for the view that multisensory integration of motion signals can occur at a perceptual level.

Auditory Perception↗

PubMed2004

Time estimation: the effect of cortically mediated attention.

Do people tend to underestimate time when their attention is engaged? Studies supporting this idea have routinely confounded attentional manipulations with changes in other factors, such as response complexity and memory load. The aim of the present study was to obtain the first direct evidence that attentional engagement mediated by cortical brain mechanisms affects time estimation. Participants were asked to perform a visual search task that either should not demand attention (simple feature search) or should demand cortical attentional engagement (conjunction search). Observers searched through 2, 4, 8, 16, 24, 32, or 40 items, for blocks of 40 or 60 trials. At the conclusion of each block participants were required to provide a written estimate of block duration. This time estimate was prospective in nature because subjects knew in advance that they would be asked to produce the estimate. Results showed that an attentionally demanding conjunction search task produced a large underestimation of time. And as the engagement of attention increased so did the underestimation of time. These findings provide strong support for an attentional model of prospective time estimation that is subserved by cortical brain mechanisms.

Adolescent↗

PubMed2004

Flexible and abstract resolutions to crossmodal conflicts.

Participants judged whether two sequential visual events were presented for the same length of time or for different lengths of time, while ignoring two irrelevant sequential sounds. Sounds could be either the same or different in terms of their duration or their pitch. When the visual stimuli were in conflict with the sound stimuli (e.g., visual events were the same, but the sounds were different) performance declined. This was true whether sounds varied in duration or in pitch. The influence of sounds was eliminated when visual duration discriminations were made easier. Together these results demonstrate that resolutions to crossmodal conflicts are flexible across the neural and cognitive architectures. More importantly, they suggest that interactions between modalities can span to abstract levels of same/different representations.

Attention↗

PubMed2004

Right hemisphere involvement in the attentional blink: evidence from a split-brain patient.

When two masked targets are presented in a rapid sequence, correct identification of the first hinders identification of the second. This attentional blink (AB) is thought to be the result of capacity limitations in visual information processing. Neuropsychological and neuroimaging evidence implicated the right hemisphere as the source of this processing limitation. We investigated this idea by testing a split-brain patient (JW) in a modified AB task. The targets were presented in the same visual field (VF), and thereby to the same hemisphere, or in different VFs. We observed evidence of an AB both when the targets were presented to the same hemisphere and when the targets were presented to different hemispheres. However, the AB was more severe when the second target was presented to the RH. Our results are consistent with the notion that the right hemisphere plays a critical, but not unique, role in limited-capacity visual processing.

Attention↗

PubMed2004

Seeing the light: Adapting luminance reveals low-level visual processes in the attentional blink.

It is widely assumed that high-level visual processes subserve the attentional blink (AB). Recent evidence from studies of visual masking during the AB that were designed to directly test the contributions of high-level masking effects, however, have failed to provide empirical support for this position. The implication is that low-level visual processes are crucial to the AB. We tested this idea by manipulating adapting luminance in a standard AB paradigm. Consistent with the involvement of low-level neural mechanisms, the AB effect interacted with adapting luminance such that an AB was revealed only under photopic (light adapted) viewing conditions.

Adaptation, Ocular↗

PubMed2004

Can semantic information be transferred between hemispheres in the split-brain?

Data from experiments with split-brain patients, who have had their left and right hemispheres disconnected, suggests a remarkable specialization of function within each hemisphere. At the same time, these patients conduct their daily lives with great proficiency. This ability suggests that some information integral to coordinated function between the hemispheres is available in the absence of the corpus callosum. Is information about the semantics of words one type of information that is shared? An experiment by suggests that it may be. Lambert reported that living/nonliving word categorization was delayed when disconnected hemispheres processed words belonging to the same category. Although other interpretations are plausible, Lambert described this effect as having a semantic source. We attempted to replicate the original effect with two additional split-brain patients, J.W. and V.P., and to extend the original design to clarify the source of the putative semantic effect. Our results indicate that any semantic interaction between the split hemispheres is not reliable. As such our study adds to the growing literature indicating that subcortical transfer of semantic information is more illusory than real.

Analysis of Variance↗

PubMed2004

The eyes have it!: an fMRI investigation.

For the past several years it has been thought that cues, such as eye direction, can trigger reflexive shifts in attention because of their biological relevance and their specialized neural architecture. However, very recently, reported that other stimuli, such as arrows, trigger reflexive shifts in attention in a manner that is behaviourally identical to those triggered by eyes. Nevertheless these authors speculated that reflexive orienting to gaze direction may be subserved by a neural system-the superior temporal sulcus (STS)-that is specialized for processing eyes. The present study presents fMRI data that provide direct and compelling empirical support to this proposal. Subjects were presented with fixation stimuli that, based on instruction, could be perceived as eyes or as another type of directional cue. Both produced equivalent shifts in reflexive attention, replicating Ristic et al. However, the neural systems subserving the two forms of orienting were not equivalent-with the STS being engaged exceptionally when the fixation stimulus was perceived as eyes.

Adult↗

PubMed2004

The effect of hemispatial neglect on the perception of centre.

Highly variable bisection performance in neglect patients has been attributed to an increased 'zone of indifference'. The indifference zone indicates the discrepancy between two line lengths which are judged as equal in length. Following this argumentation, the central area of a line should be expanded in neglect patients. The present two experiments investigated for the first time the expansion of the central area using a modified version of the Landmark Task. The location of a central or asymmetrical bisection mark on a horizontal line had to be judged (centre/left/right). In both experiments neglect patients, unlike healthy and patient controls, showed clear deficits in judging the location of the mark correctly and tended to judge asymmetrical marks of up to 4 cm as centrally positioned. The results are in agreement with and provide the first clear evidence of an enlarged perceptual zone of indifference in patients with hemispatial visual neglect.

Aged↗

PubMed2004

Multisensory executive functioning.

To better understand the prefrontal circuitry that putatively supports executive functions, such as those involved in switching tasks, we asked whether a current task set is open equally to receiving information from any sensory modality or if it is to some degree modality-specific. Subjects were presented with a sequence of digits to be classified as either odd/even or greater/less than five. The digits were either auditory or visual, with the modality varying randomly. Results demonstrated a reaction time (RT) cost associated with switching between tasks and also an unexpected cost of switching between modalities. When both modality and task switched, the two costs were greater than either of the costs alone, but significantly less than predicted simply by summing the two costs together (i.e., they were underadditive). These data indicate that the frontal mechanisms that allow for a switch in task are only partially modality-specific. Current theories of executive function must be adapted to account for this finding. We also suggest that the present paradigm is amenable to future research aimed at determining precisely how modalities are linked within a task set.

Acoustic Stimulation↗

PubMed2004

Integration of competing saccade programs.

Reflexive responses are often in direct competition with voluntary control. We test two opposing explanations for how this competition is resolved with respect to eye movements. One states that the quickest activation wins. The other states that the strongest activation wins. We show that an eye movement is executed according to the strongest activation, with the competition being staged at a common subcortical site.

Humans↗

PubMed2004

Hemisphere differences in conscious and unconscious word reading.

Hemisphere differences in word reading were examined using explicit and implicit processing measures. In an inclusion task, which indexes both conscious (explicit) and unconscious (implicit) word reading processes, participants were briefly presented with a word in either the right or the left visual field and were asked to use this word to complete a three-letter word stem. In an exclusion task, which estimates unconscious word reading, participants completed the word stem with any word other than the prime word. Experiment 1 showed that words presented to either visual field were processed in very similar ways in both tasks, with the exception that words in the right visual field (left hemisphere) were more readily accessible for conscious report. Experiment 2 indicated that unconsciously processed words are shared between the hemispheres, as similar results were obtained when either the same or the opposite visual field received the word stem. Experiment 3 demonstrated that this sharing between hemispheres is cortically mediated by testing a split-brain patient. These results suggest that the left hemisphere advantage for word reading holds only for explicit measures; unconscious word reading is much more balanced between the hemispheres.

Adult↗

PubMed2004

Attentional effects of counterpredictive gaze and arrow cues.

The authors used counterpredictive cues to examine reflexive and volitional orienting to eyes and arrows. Experiment 1 investigated the effects of eyes with a novel design that allowed for a comparison of gazed-at (cued) target locations and likely (predicted) target locations against baseline locations that were not cued and not predicted. Attention shifted reflexively to the cued location and volitionally to the predicted location, and these 2 forms of orienting overlapped in time. Experiment 2 discovered that another well-learned directional stimulus, an arrow, produced a different effect: Attention was shifted only volitionally to the predicted location. The authors suggest that because there is a neural architecture specialized for processing eyes, gaze-triggered attention is more strongly reflexive than orienting to arrows.

Adult↗

PubMed2004

Cross-modal dynamic capture: congruency effects in the perception of motion across sensory modalities.

This study investigated multisensory interactions in the perception of auditory and visual motion. When auditory and visual apparent motion streams are presented concurrently in opposite directions, participants often fail to discriminate the direction of motion of the auditory stream, whereas perception of the visual stream is unaffected by the direction of auditory motion (Experiment 1). This asymmetry persists even when the perceived quality of apparent motion is equated for the 2 modalities (Experiment 2). Subsequently, it was found that this visual modulation of auditory motion is caused by an illusory reversal in the perceived direction of sounds (Experiment 3). This "dynamic capture" effect occurs over and above ventriloquism among static events (Experiments 4 and 5), and it generalizes to continuous motion displays (Experiment 6). These data are discussed in light of related multisensory phenomena and their support for a "modality appropriateness" interpretation of multisensory integration in motion perception.

Auditory Perception↗

PubMed2004

Influence of inter-item symmetry in visual search.

Does visual search involve a serial inspection of individual items (Feature Integration Theory) or are items grouped and segregated prior to their consideration as a possible target (Attentional Engagement Theory)? For search items defined by motion and shape there is strong support for prior grouping (Kingstone and Bischof, 1999). The present study tested for grouping based on inter-item shape symmetry. Results showed that target-distractor symmetry strongly influenced search whereas distractor-distractor symmetry influenced search more weakly. This indicates that static shapes are evaluated for similarity to one another prior to their explicit identification as 'target' or 'distractor'. Possible reasons for the unequal contributions of target-distractor and distractor-distractor relations are discussed.

Adult↗

PubMed2004

Attentional capture modulates perceptual sensitivity.

The present study was designed to determine the spatial distribution of attention in displays in which an irrelevant color singleton was present. The results show that the presence of an irrelevant color singleton modulates target detectability (d'). The presence of an irrelevant singleton reduces the gain for input at the target location, particularly when the irrelevant color singleton was close to the target singleton. In line with earlier claims, it is argued that the capture of attention by the irrelevant singleton causes a reduced sensory input at the target location.

Attention↗

PubMed2004

Inhibiting prepared and ongoing responses: is there more than one kind of stopping?

Inhibiting movements has been investigated widely using the countermanding (stop signal) paradigm. Although it has been assumed that response inhibition, as measured by the countermanding task, generalizes to all forms of stopping, this has never been tested. In the present study, stopping performance in the countermanding paradigm was compared with stopping performance in a new paradigm in which a continuous-tracking task was used. Although stimulus presentations were matched across paradigms, the two tasks differed in the type of stopping required. In the countermanding paradigm, response inhibition latency was measured prior to response execution-this is, it was inferred from the successful withholding of a go response. In the new paradigm, response inhibition was carried out after response execution-that is, it was measured as the time to begin stopping a continuous tracking response. Results indicated that stopping latencies between the two paradigms were highly correlated, providing strong evidence that stopping an unexecuted response engages the same mechanisms as stopping an ongoing response.

Adult↗