Allocation of visual attention depends on type of precue

To distinguish between theoretical concepts of how attention is allocated, participants were presented with different types of precues in 6 experiments. In 1 condition with 100% valid precues (Experiments 1 and 2), the time course of attention effects revealed that (a) higher accuracy was obtained with dynamic multiple-element precues (MEPs in which the unique element was defined by apparent motion) than with static MEPs, in which the elements did not move once they were presented (Cheal & Chastain, 1998); (b) a longer precue-target interval (stimulus-onset asynchrony; SOA) was needed to reach asymptote accuracy with dynamic MEPs than with dynamic single-element precues (SEPs); and (c) all dynamic precues (both MEPs and SEPs) resulted in a decline in accuracy at long SOAs. These results suggest that static and dynamic MEPs result in delayed engagement of attention relative to SEPs. Further, a decline in accuracy at long intervals is associated with static and dynamic SEPs and dynamic MEPs, but not with static MEPs. With irrelevant precues (Experiments 3 to 5), there was capture by precues in which the unique element moved briskly, smoothly, or abruptly, or simply flashed on and off, although there were differences in the amount of capture. The strongest capture occurred with smooth movement in static background elements and the weakest with smooth movement in abruptly moving background elements. It was shown in Experiment 6 that a static MEP will not capture attention if one element changes to a unique brightness near the time of precue onset, but if the element changes after 1,000 ms, it will capture attention. The authors suggest that different types of precues result in unequal influence of endogenous and exogenous components of attention, even when the same targets are used. In addition, they show that neither singleton detection mode nor contingent involuntary orienting is necessary for the capture of attention.     

Large and rapid improvement in form discrimination accuracy following a location precue

Processing of a visual stimulus can be improved by precuing its location. Most previous precue studies have used reaction time as the dependent measure and have found large effects; but when form discrimination accuracy has been used, precue effects have been relatively small. The present experiments yielded large, short-latency precue effects on form discrimination accuracy. A small square precue was briefly presented near one of four possible target locations. Then one of four possible targets (T-like figures) was presented in each location, followed by a mask. Observers attempted to identify the target that had been presented in the cued location. In experiment 1, target duration, cue-to-target distance, and cue-target onset asynchrony (SOA) were varied. Target discriminability (d') increased markedly with increasing precue-target SOA, even at very short SOAs. Thus, there was no evidence for a delay in the onset of precue effects (caused, for example, by the need to shift attention across the visual field). Performance was best for precues that were closest to the target, thus ruling out a forward masking explanation of the effect. Finally SOA and target duration interacted strongly - longer precue SOAs resulted in larger effects of target duration. In experiment 2, this interaction was replicated using an additional target duration and longer SOAs. One interpretation of this result is that focal attention increases the rate at which information can be extracted from a visual location.     

On the status of location in visual attention

The authors propose a distinction between four issues underlying the debate on the status of location in visual selective attention. Three of them concern the representation within which attention operates. The grouping question focuses on whether or not this representation segments the visual field into perceptual groups. The space-invariance question focuses on whether it describes objects in spatio-topic or in space-invariant coordinates. Finally, the feature-coding question concerns whether or not it contains information about objects' non-spatial features. The last issue focuses on whether or not attention can be guided preattentively towards items possessing certain pre-specified physical properties other than location, and is referred to as the attentional-guidance question. A critical survey of the literature within the proposed framework is presented. Based on its conclusions, the status of location in current research is outlined, and avenues for further research are suggested.     

Top-down search for color prevents voluntary directing of attention to informative singleton cues

Visuo-spatial attention can be directed in a top-down controlled way to search for color targets and it can be captured by color contrasts, regardless of color identity. Here we tested whether participants can both search for a particular color target (e.g., red) and make use of a color-contrast cue that predicted the target's most likely position to direct their attention voluntarily. Our results show that this was impossible for the participants. Results support that top-down search for particular colors is incommensurate with directing attention to just any color contrast. The results are discussed in light of the current debates concerning the roles of color and color contrast for visuo-spatial attention.     

Awareness is necessary for extracting patterns in working memory but not for directing spatial attention

The contents of working memory (WM) have predominantly been viewed as necessarily conscious. However, recent findings suggest otherwise. Here we investigate whether visual WM can represent subliminal stimuli, such that the positions of an invisible moving object can be extrapolated or learned about in terms of their task-relevant predictive power. We presented a moving cue subliminally and measured subjects' performance on an orientation-discrimination task at the naturally anticipated location on the cue's trajectory and at variably predictable off-trajectory locations. Our data show that orientation discriminability at the on-trajectory location was not significantly different from that at a nearby off-trajectory location. However, orientation discriminability at locations near the final position of the cue was significantly better than that at distal locations. This finding suggests that a moving object can still attract attention when presented subliminally. In contrast, the dynamic trajectory of the object and its task-relevant predictive patterns may not be monitored and maintained in visual WM. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Spatial frequency and selective attention to spatial location

The effect of spatial attention on the detectability of gratings of different spatial frequency was measured using a probe technique. Three experiments are reported in which the detectability of full-field probe gratings was measured while subjects analyzed stimuli presented in either the central or the peripheral visual field. Selective attention to peripheral stimuli produced a facilitation at low frequencies and a decrement at high frequencies. These effects disappeared under forced-choice presentation.     

Effects of attention during encoding on sex differences in object location memory

Attention plays a key role in memory processes and has been widely studied in various memory tasks. The role of attention in sex differences in object location memory is not clearly understood. In the present study, two experiments involving 186 participants and using an object array presented on paper were conducted to examine two encoding conditions: incidental and intentional. In each experiment, the participants were randomly assigned to divided versus full attention conditions. In the first experiment, which involved incidental encoding, women outperformed men in memorising location‐exchanged objects in both the full and in the divided attention condition. In the second experiment, which involved intentional encoding, women outperformed men in memorising location‐exchanged objects in the full attention condition, but not the divided attention condition. These findings deepen our knowledge regarding the role of attention in object location memory, specifically in terms of the conditions under which females have an advantage for detecting changes in an array of objects.     

Directing spatial attention towards the illusory location of a ventriloquized sound

In this study, we examined whether ventriloquism can rearrange external space on which spatial reflexive attention operates. The task was to judge the elevation (up vs down) of auditory targets delivered in the left or the right periphery, taking no account of side of presentation. Targets were preceded by either auditory, visual, or audiovisual cues to that side. Auditory, but not visual cues had an effect on the speed of auditory target discrimination. On the other hand, a ventriloquized cue, consisting of a tone in central location synchronized with a light flash in the periphery, facilitated responses to targets appearing on the same side as the flash. That effect presumably resulted from the attraction of the apparent location of the tone towards the flash, a well-known manifestation of ventriloquism. Ventriloquism thus can reorganize space in which reflexive attention operates.     

Mapping the timecourse of goal-directed attention to location and colour in human vision

Goal-directed attention prioritises perception of task-relevant stimuli according to location, features, or onset time. In this study we compared the behavioural timecourse of goal-directed selection to locations and colours by varying the stimulus-onset asynchrony (SOA) between cue and target in a strategic cueing paradigm. Participants reported the presence or absence of a target following prior information regarding its location or colour. Results revealed that preparatory selection by colour is more effective at enhancing perceptual sensitivity than selection by location, even though both types of cue provided equivalent overall information. More detailed analysis revealed that this advantage arose due a limitation of spatial attention in maintaining a sufficiently broad focus (>2°) for target detection across multiple stimuli. In contrast, when target stimuli fell within 2° of the spatial attention spotlight, the strategic advantages and speed of spatial and colour attention were equated. Our findings are consistent with the conclusion that, under spatially optimal conditions, prior spatial and colour information are equally proficient at guiding top-down selection. When spatial locations are ambiguous, however, colour-based selection is the more efficient mechanism.     

Detectability as a function of spatial location: effects of selective attention

In a series of previous reports we have described differences in detectability of a target in a background of nontarget patterns as a function of its spatial location. These differences, referred to as a "detectability gradient," have been attributed to target detection accomplished by a serial processing mechanism--a scan. The mathematical model of such a mechanism, developed in the previous report, is equally applicable to a series of attentional shifts or to a perceptual, i.e., a preattentive, mechanism. The present experiments were designed to test the hypothesis that this scan is attentional in nature. The results provide additional evidence for the scanning hypothesis but do not support the view that this scan represents a series of attentional shifts.     

Multiple-element line segment precues: Orientation and location effects on attention

Three experiments were conducted to examine the hypothesis that a uniquely oriented line segment located at the end of the directional flow produced by the alignment of the long axes of identically oriented background segments will not be detected as rapidly as when the segment appears at locations within the flow. The hypothesis was supported with response time measured in Experiment 1. A location-cuing task was used in the last two experiments, with the unique segment becoming a precue to indicate the location of an upcoming target character; accuracy was the dependent measure. Poorer detection of the unique segment at end-of-flow locations was shown not to be due to a local configuration effect produced by the uniquely oriented segment in conjunction with the segment on either side. The time course of attentional development with multiple-segment precue displays was comparable to that with an arrow at fixation as the precue, and slower than that with a line segment appearing alone.     

Time-course of sensitivity changes as attention shifts to an unpredictable location.

Shifting visual attention is often described as analogous to a spotlight moving through empty space between locations. In the present experiment, a peripheral precue summoned attention to an initial location, and 200 ms later a second peripheral cue appeared beside one of two possible second locations, each 14 degrees away from the initial location. The target was twice as likely to appear at the location that had been indicated by the immediately preceding cue as at the location that had been previously cued or that would be cued. Fine-grained temporal analyses indicated that, as attention was shifted, sensitivity to information at the second location gradually increased while sensitivity at the first location simultaneously decreased. Average sensitivity over the two locations during the shift remained significantly greater than average sensitivity immediately following the initial precue. In contrast, an attentional "spotlight" moving from the first to the second location would produce a decrease in average sensitivity to its initial level while the spotlight was between locations.     

Retinal location and its effect on the spatial distribution of visual attention

A series of studies tested for distractor compatibility effects across wide target/distractor distances (0.6 degree to 20 degrees of visual angle). The effects of precue condition, constant/varied target location, horizontal/vertical distractor distance, and foveal/peripheral presentation were studied. Results show strong compatibility effects across wide distances when distractors are at peripheral retinal locations. When both stimuli were presented at the same peripheral location in opposite hemifields, compatibility effects were evident within an area of at least 2.5 degrees of visual angle. In contrast, when foveally placed distractors were used, compatibility effects were found primarily with target letters positioned near. The findings suggest that distance effects are not homogeneous across retinal location.     

The effects of endogenous attention and stimulus onsets on encoding target location

The effects of endogenously attended and non-attended stimulus onsets on spatial stimulus encoding of a target were explored in a Simon task. In each experiment participants made speeded left or right key-press responses to the colour of a target that followed a cueing display consisting of several shapes. The target appeared within some shapes and not others. The target's spatial code as measured by a Simon task was its location relative to possible target positions and relative to the centre of the display. Target location was not coded relative to the positions of onset shapes that could not contain a target. These spatial coding effects were found at cue-target intervals of 50, 300, and 1000 ms. The data indicate that target location is defined relative to the distribution of endogenous attention and reference frames aligned with the centre of the display and that the spatial code assigned to a target is not affected when attention is shifted in the target's direction.     

Further evidence in favor of prior entry from endogenous attention to a location in space

Titchener’s (1908) law of prior entry states that “the object of attention comes to consciousness more quickly than the objects which we are not attending to,” or otherwise, that attended stimuli are perceived earlier than unattended stimuli. Shore, Spence, and Klein (Psychological Science, 12, 205–212. doi: 10.1111/1467-9280.00337, 2001) showed that endogenous visuospatial orienting does in fact elicit prior-entry effects, albeit to a smaller degree than does exogenous visuospatial orienting. In disagreement with this finding, Schneider and Bavelier (Cognitive Psychology, 47, 333–366. doi: 10.1016/S0010-0285(03)00035-5, 2003) found no effect of their instruction to attend. They concluded that nonattentional effects could masquerade as prior entry, which could account for findings such as those in Shore et al.’s endogenous condition. We investigated this empirical and theoretical discord by replicating the temporal-order judgment task used by Shore, Spence, and Klein, while manipulating and measuring endogenous orienting by way of an orthogonal color probe task. We showed evidence of prior entry as a consequence of endogenous orienting, supporting the conclusions of Shore, Spence, and Klein.     

On the costs and benefits of directing attention towards or away from threat-related stimuli: A classical conditioning experiment

In attentional bias modification programs, individuals are trained to attend away from threat in order to reduce emotional reactivity to stressful situations. However, attending towards threat is considered to be a prerequisite for fear reduction in other models of anxiety. We compared both views by manipulating attention towards or away from an acquired signal of threat. The strength of extinction and reacquisition was assessed with threat and US-expectancy ratings. We found more extinction in the attend towards threat group, compared to both the attend away from threat group and a control group in which attention was not manipulated. The results are in line with the Emotional Processing Theory and cognitive accounts of classical conditioning.     

Effects of location and form cuing on the allocation of attention in the visual field

Two experiments were conducted which tested the effect of two different types of cues on the allocation of attention in the visual field. Subjects responded to a target appearing either 6.5 degrees to the right or to the left of fixation in a field filled with small randomly positioned line segments. The target form was either a circle or diamond in which a horizontal or vertical line segment was positioned. Subjects made a speeded discrimination response on the basis of the orientation of this line segment. In the first experiment, there was always one target at each trial. In the second experiment, both circle and diamond were presented left or right of fixation simultaneously whereby the line segment only appeared in one of the forms. In different conditions, the most likely target location (left or right) and form (circle or diamond) were cued. Control conditions served as a baseline for determining costs and benefits. Reaction time measures showed that the validity of the location cue resulted in both costs and benefits, whereas the validity of the form cue had no such effects. The results cannot be reconciled with the claim of zoom lens theories that spatial attention can switch between different modes of operations. They are also at odds with theories that claim that attention has no spatial locus. The results are consistent with a simple spotlight theory in which spatial attention involves selecting a particular restricted area of the visual field for which the perceptual efficiency is enhanced.     

Active inhibition of a distractor word: the distractor precue benefit in the Stroop color-naming task

The current study investigated attentional control through active inhibition of the identity of the distractor. Adapting a Stroop paradigm, the distractor word was presented in advance and made to disappear, followed by the presentation of a Stroop stimulus. Participants were instructed to inhibit the distractor in order to reduce its interference. Experiments 1 and 2 demonstrated that the distractor precue facilitated Stroop color naming by reducing Stroop interference. Experiment 3 demonstrated beneficial effects of the distractor precue when congruent trials were introduced. Experiment 4 showed that the distractor precue benefit was observed when the cue and target were in different forms. Experiment 5 indicated that if the item used as the cue became the target, naming it took longer in order to overcome the inhibitory effect. Experiment 6 demonstrated that the benefit of the distractor precue was not observed when the cue was uninformative. Finally, Experiment 7 demonstrated that active inhibition required working-memory resources to operate. This study suggests that the best explanation for the distractor precue benefit is the active inhibition account.