Action relations, semantic relations, and familiarity of spatial position in Balint’s syndrome: Crossover effects on perceptual report and on localization

We contrasted effects of the action relationship between objects, relative to effects of semantic relation and familiarity of spatial location, in a patient with Balint’s syndrome. We found enhanced perceptual report of objects placed in the correct colocations for action in comparison with when the objects (1) were placed in incorrect locations for action (Experiment 1), (2) were associatively related (Experiment 2), or (3) fell in familiar locations but were not action related (Experiment 4). In contrast, the ability to localize the objects was affected by whether the objects were in familiar as opposed to unfamiliar locations with respect to one another. Action relations between objects facilitate joint attention to both objects but do not facilitate binding to location. Familiar spatial relations facilitate spatial binding, but do not cue joint attention to the stimuli. Effects of action relation on attention and localization can be dissociated from effects of semantic relationship and familiarity of spatial location on attention and localization.     

Tactile "capture" of audition

Previous research has demonstrated that the localization of auditory or tactile stimuli can be biased by the simultaneous presentation of a visual stimulus from a different spatial position. We investigated whether auditory localization judgments could also be affected by the presentation of spatially displaced tactile stimuli, using a procedure designed to reveal perceptual interactions across modalities. Participants made left-right discrimination responses regarding the perceived location of sounds, which were presented either in isolation or together with tactile stimulation to the fingertips. The results demonstrate that the apparent location of a sound can be biased toward tactile stimulation when it is synchronous, but not when it is asynchronous, with the auditory event. Directing attention to the tactile modality did not increase the bias of sound localization toward synchronous tactile stimulation. These results provide the first demonstration of the tactile capture of audition.     

Tactile “capture” of audition

Previous research has demonstrated that the localization of auditory or tactile stimuli can be biased by the simultaneous presentation of a visual stimulus from a different spatial position. We investigated whether auditory localization judgments could also be affected by the presentation of spatially displaced tactile stimuli, using a procedure designed to reveal perceptual interactions across modalities. Participants made left—right discrimination responses regarding the perceived location of sounds, which were presented either in isolation or together with tactile stimulation to the fingertips. The results demonstrate that the apparent location of a sound can be biased toward tactile stimulation when it is synchronous, but not when it is asynchronous, with the auditory event. Directing attention to the tactile modality did not increase the bias of sound localization toward synchronous tactile stimulation. These results provide the first demonstration of the tactilecapture of audition.     

Effects of attention on localization of stimuli in the visual field

Subjects localized a small letter that appeared inside one of three large circles that was either validly or invalidly cued. The results indicated that, although unattended stimuli were localized fairly accurately, attention still improved localization. Moreover, the results revealed a greater dispersion of localization responses along the horizontal axis and also showed that mislocalization of attended peripheral stimuli is biased toward the periphery.     

A multisensory interaction effect in the conceptual realm of time

Recent studies on the conceptualization of abstract concepts suggest that the concept of time is represented along a left-right horizontal axis, such that left-to-right readers represent past on the left and future on the right. Although it has been demonstrated with strong consistency that the localization (left or right) of visual stimuli could modulate temporal judgments, results obtained with auditory stimuli are more puzzling, with both failures and successes at finding the effect in the literature. The present study supports an account based on the relative relevance of visual versus auditory-spatial information in the creation of a frame of reference to map time: The auditory location of words interacted with their temporal meaning only when auditory information was made more relevant than visual spatial information by blindfolding participants.     

When here becomes there: attentional distribution modulates foveal bias in peripheral localization

Much research concerning attention has focused on changes in the perceptual qualities of objects while attentional states were varied. Here, we address a complementary question--namely, how perceived location can be altered by the distribution of sustained attention over the visual field. We also present a new way to assess the effects of distributing spatial attention across the visual field. We measured magnitude judgments relative to an aperture edge to test perceived location across a large range of eccentricities (30°), and manipulated spatial uncertainty in target locations to examine perceived location under three different distributions of spatial attention. Across three experiments, the results showed that changing the distribution of sustained attention significantly alters known foveal biases in peripheral localization.     

Localization of electrocutaneous stimuli on the fingers and forearm: Effects of electrode configuration and body axis

Four experiments were done on the effects of electrode configuration (concentric vs. unifocal) and body axis (longitudinal vs. transverse) on localization of electrocutaneous pulse stimuli at the fingers and forearm. Subjects pointed to the apparent location of current pulses. For the transverse placement of electrodes, pulses were localized correctly, whatever the configuration and the body site might be. In addition, intrasubject variability at the forearm was smaller for the transverse axis than for the longitudinal axis. For the longitudinal placement of electrodes, pulses were localized as a function of configuration and body site. At the fingers, concentric electrodes provided precise localization but unifocal electrodes provided a great mislocalization; and intrasubject variability of localization was larger for the unifocal electrodes than for the concentric electrodes. At the forearm, whatever the configuration might be, the pulses were localized more proximally than the stimulus site; and intrasubject variability of localization did not differ between the configurations. These results are related to Boring’s anchor theory, apparent distance between two points, and the localization of other somatosensory stimuli.     

Effect of negative emotion on visual attention: Automatic capture by fear‐related stimuli1

Abstract: In this study, we examined the effect of threatening pictures (e.g., snakes and spiders) on control of spatial attention using a probe detection task. In addition to attentional capture by the threatening stimuli (Unpredictable task), the effects of affective valence of the pictures on the voluntary control of attention were explored (Predictable task). Results showed that reaction time (RT) was facilitated to the probe that appeared at the location of threatening stimuli when it occurred in the right visual field (but not in the left visual field), indicating that attention was captured automatically, at least in this visual field. However, when participants were able to predict the probe location, the attentional gains increased similarly for all the conditions (composed of visual field by picture type combinations) relative to those of Unpredictable task, with no indication of deferred deployment of attention to threatening stimuli. The results of this study suggested that the emotional valence, particularly negative valence, affected the automatic control of attention. This effect differed between the two visual fields in which emotional stimuli occurred.     

Beyond fear: rapid spatial orienting toward positive emotional stimuli

There is much empirical evidence for modulation of attention by negative -- particularly fear-relevant -- emotional stimuli. This modulation is often explained in terms of a fear module. Appraisal theories of emotion posit a more general mechanism, predicting attention capture by stimuli that are relevant for the needs and goals of the organism, regardless of valence. To examine the brain-activation patterns underlying attentional modulation, we recorded event-related potentials from 20 subjects performing a dot-probe task in which the cues were fear-inducing and nurturance-inducing stimuli (i.e., anger faces and baby faces). Highly similar validity modulation was found for the P1 time-locked to target onset, indicating early attentional capture by both positive and negative emotional stimuli. Topographic segmentation analysis and source localization indicate that the same amplification process is involved whether attention orienting is triggered by negative, fear-relevant stimuli or positive, nurturance-relevant stimuli. These results confirm that biological relevance, and not exclusively fear, produces an automatic spatial orienting toward the location of a stimulus.     

An ERP investigation of location invariance in masked repetition priming

In an experiment combining masked repetition priming and the recording of event-related potentials (ERPs) the location of prime stimuli relative to centrally located target words was manipulated. Prime words could appear at the same location as targets or shifted one letter position to the right or to the left. Repetition priming effects (amplitude differences across the repeat vs. unrelated prime conditions) were found in a series of ERP components starting at around 100 msec posttarget onset. The earliest of these, the N/P150 component, was found to be sensitive to prime location. Repetition priming was only apparent with centrally located primes in this component. Repetition priming effects in later components (N250 and N400), on the other hand, were not affected by prime location. The results are interpreted in terms of location-specific letter detectors that map onto a higher level, location-invariant orthographic code for printed words.     

Attending, ignoring, and repetition: on the relation between negative priming and inhibition of return

A series of spatial localization experiments is reported that addresses the relation between negative priming and inhibition of return. The results of Experiment 1 demonstrate that slowed responses to repeated location stimuli can be obscured by repetition priming effects involving stimulus dimensions other than spatial location. The results of Experiments 2, 3A, and 3B demonstrate that these repetition priming effects may occur only when participants are required to respond to the prime display. Together, these results suggest that differences between attended and ignored repetition effects in selective attention studies of spatial localization do not provide a basis for distinguishing between spatial negative priming and inhibition of return.     

Visual attention to color: parvocellular guidance of attentional resources?

Although transient changes in luminance have been well documented to automatically attract attention to their location, experiments looking at abrupt changes in color have failed to find similar attentional capture. These results are consistent with current theories of the role of the magnocellular (M) and parvocellular (P) streams that postulate that the M stream, which is "color-blind," plays the dominant role in guiding attention and eye movements. The experiment reported here used stimuli that contained only information defined by color, and masked residual luminance information with dynamic noise, to assess the capacity of purely chromatic cues to automatically guide spatial attention. Such stimuli were as effective as those containing large luminance signals in guiding attention. To the extent that these purely chromatic signals isolated the P stream, these results suggest that this stream is also capable of automatic attentional capture. Hence, color vision not only aids target identification but also is a strong aid for target detection and localization.     

Chicks prefer to peck at insect-like elongated stimuli moving in a direction orthogonal to their longer axis

Spontaneous preferences towards possible prey have been little investigated using targets in motion. Preferences of domestic chicks (Gallus gallus) to peck at video-images of stimuli representing live insects moving along their longer body axis (i.e. “forwards”) or along the shorter body axis (i.e. “sideways”) were investigated. Chicks presented with both types of stimulus displayed a significant preference for pecking at stimuli moving sideways. This preference was already present on day 1 post-hatching, and it strengthened on day 6 for those chicks that had experienced pecking at live insects. Head angles used to fixate the stimuli prior to pecking were also analysed and were consistent (i.e. 30°–35° and 60°–65°) with those reported for fixation of non-edible targets (larger stimuli at a distance). In a first control experiment the same video-presented stimuli were used but the insect’s legs were removed to reduce flickering. In a second control experiment, paper-printed images of the whole insect were used. In both cases, the sideways direction of movement was clearly preferred. Overall, our data show that chicks have a spontaneous preference to peck at video-images resembling live insects moving along their shorter body axis. Sideways movement may constitute a crucial signal attracting chicks’ attention and enhancing predatory responses possibly because of stronger stimulation of motion detectors.     

Do working memory-driven attention shifts speed up visual awareness?

Previous research has shown that content representations in working memory (WM) can bias attention in favor of matching stimuli in the scene. Using a visual prior-entry procedure, we here investigate whether such WM-driven attention shifts can speed up the conscious awareness of memory-matching relative to memory-mismatching stimuli. Participants were asked to hold a color cue in WM and to subsequently perform a temporal order judgment (TOJ) task by reporting either of two different-colored circles (presented to the left and right of fixation with a variable temporal interval) as having the first onset. One of the two TOJ circles could match the memory cue in color. We found that awareness of the temporal order of the circle onsets was not affected by the contents of WM, even when participants were explicitly informed that one of the TOJ circles would always match the WM contents. The null effect of WM on TOJs was not due to an inability of the memory-matching item to capture attention, since response times to the target in a follow-up experiment were improved when it appeared at the location of the memory-matching item. The present findings suggest that WM-driven attention shifts cannot accelerate phenomenal awareness of matching stimuli in the visual field.     

The representational locus of spatial influence on backward inhibition

When one is sequentially switching among three tasks, performance is impaired when tasks alternate (ABA) relative to when one is switching between all three tasks (CBA), an effect known as backward inhibition (BI). BI is not observed when component tasks are uniquely located in space, however (Arbuthnott, 2005). In this study, the locations of task precues and target stimuli were manipulated independently to determine whether this elimination of BI is related to distinct cue location or to distinct target location. Results clearly indicated that BI is eliminated with distinct cue localization independent of the location of target stimuli. This indicates that BI, which reflects suppression of task-set representations, can be influenced by cue characteristics that are associated with task representations.     

Spatial processing and perceptual sequence learning in SRT tasks

We investigated the influence of processing relevant spatial information on learning a probabilistic sequence of irrelevant locations. Using the SRT design of Remillard (2003), we found that spatial perceptual learning occurs with paired but not with single targets. The pairs of targets consisted of the same stimuli, but in a different order, so that responses could have been based on the left-right location of an element, relative to the other element of the pair. The prerequisite of spatial pairs of targets suggests that spatial processing of relevant information plays a crucial role in perceptual location learning. In addition, spatial perceptual learning only took place when the target pair was presented together with other stimuli, but was absent when the target pair was presented in a blank field. Since in the latter case attention is automatically captured, this suggests that sequence learning requires endogenous attention.     

Investigating the parameters of transsaccadic memory: inhibition of return impedes information acquisition near a saccade target

A limited amount of visual information is retained between saccades, which is subsequently stored into a memory system, such as transsaccadic memory. Since the capacity of transsaccadic memory is limited, selection of information is crucial. Selection of relevant information is modulated by attentional processes such as the presaccadic shift of attention. This involuntary shift of attention occurs prior to execution of the saccade and leads to information acquisition at an intended saccade target. The aim of the present study was to investigate the influence that another attentional effect, inhibition of return (IOR), has on the information that gets stored into transsaccadic memory. IOR is the phenomenon where participants are slower to respond to a cue at a previously attended location. To this end, we used a transsaccadic memory paradigm in which stimuli, oriented on a horizontal axis relative to saccade direction, are only visible to the participant before executing a saccade. Previous research showed that items in close proximity to a saccade target are likely to be reported more accurately. In our current study, participants were cued to fixate one of the stimulus locations and subsequently refixated the centre fixation point before executing the transsaccadic memory task. Results indicate that information at a location near a saccade landing point is less likely to be acquired into transsaccadic memory when this location was previously associated with IOR. Furthermore, we found evidence which implicates a reduction of the overall amount of elements retained in transsaccadic memory when a location near a saccade target is associated with IOR. These results suggest that the presaccadic shift of attention may be modulated by IOR and thereby reduces information acquisition by transsaccadic memory.     

Object-centered representations support flexible exogenous visual attention across translation and reflection

Visual attention can be deployed to stimuli based on our willful, top-down goal (endogenous attention) or on their intrinsic saliency against the background (exogenous attention). Flexibility is thought to be a hallmark of endogenous attention, whereas decades of research show that exogenous attention is attracted to the retinotopic locations of the salient stimuli. However, to the extent that salient stimuli in the natural environment usually form specific spatial relations with the surrounding context and are dynamic, exogenous attention, to be adaptive, should embrace these structural regularities. Here we test a non-retinotopic, object-centered mechanism in exogenous attention, in which exogenous attention is dynamically attracted to a relative, object-centered location. Using a moving frame configuration, we presented two frames in succession, forming either apparent translational motion or in mirror reflection, with a completely uninformative, transient cue presented at one of the item locations in the first frame. Despite that the cue is presented in a spatially separate frame, in both translation and mirror reflection, behavioralperformance in visual search is enhanced when the target in the second frame appears at the same relative location as the cue location than at other locations. These results provide unambiguous evidence for non-retinotopic exogenous attention and further reveal an object-centered mechanism supporting flexible exogenous attention. Moreover, attentional generalization across mirror reflection may constitute an attentional correlate of perceptual generalization across lateral mirror images, supporting an adaptive, functional account of mirror images confusion.     

Selecting spatial frames of reference for visual target localization

This study examined the selection of spatial frames of reference for target localization in visual search. Participants searched for local target characters in global character configurations. The local targets could be localized relative to the character configuration in which they were embedded or relative to the presentation screen on which the configurations were displayed. We investigated under which conditions the configurations, or the screen served as frame of reference for target localization. Three experiments revealed an increasing impact of screen-related target localization with decreasing spatial uncertainty of targets in screen-related coordinates. The results indicate the capability of the visual system to localize relevant visual stimuli with respect to those frames of reference that yield the most redundant spatial distribution of these stimuli.     

Attentional distribution in the visual field duringsame-different judgments as assessed by response competition

Judgments ofsame anddifferent on a comparison task have been found to be subject to response competition if an irrelevant stimulus is presented in the display along with the target stimuli. For example, the reaction time for judging two letters the same is markedly increased if a different but irrelevant letter is also present in the display (C. W. Eriksen, O’Hara, & B. [A.] Eriksen, 1982). We have made use of this competition effect to map the visual attentional field in two dimensions. In two experiments, we varied the size of the attended area by varying the separation of the comparison stimuli. The boundaries of the attended area were mapped by varying the location of a response-competitive irrelevant noise letter. On this task, the attended area was found to be elliptical in shape, with the location of the target stimuli defining the major axis. The minor axis of the ellipse increased in direct proportion to increases in the major axis. Rather than interpret these field effects in terms of areas of enhanced processing, we propose that instead they represent the limits or failures in inhibition of competing stimulation.