Automatic Versus Directed Attention with Single-element and Multiple-element Precues

Early perceptual interactions shape the time course of cueing

Performance in spatial cueing tasks is characterized by a rapid attentional enhancement with increasing cue-target SOA. We recently found that this enhancement function also applies when the cue and the target are presented invariably at a single central location, suggesting a universal cueing time course [Wilschut et al., 2011, PLoS ONE, 6, e27661]. However, using a very similar cueing task, Nieuwenstein et al. [2009, JoV, 9, 1-14] have found a rather different pattern, namely a U-shaped deficit in performance after a cue-like stimulus. The present study varied the properties of the cue and the target in order to investigate the mechanisms underlying the different time functions. In four experiments, cueing was found to either improve or decrease performance with increasing SOA, depending on the type of target that was used. In addition, the level of performance at the shortest cue-target intervals (33-83ms) was dependent on the relative strength of the cue and the target, akin to what has been found in visual masking studies. The results suggest that cueing shapes performance via two mechanisms, one sensory-related and one attention-related, the combination of which results in either U-shaped or monotonic patterns.

Displaywide visual features associated with a search display’s appearance can mediate attentional capture

Whether or not the capture of visual attention is driven solely by the salience of an attention-capturing stimulus or mediated by top-down control has been a point of contention since Folk, Remington, and Johnston (1992) introduced their contingent involuntary orienting hypothesis, which states that the capture of attention by a salient stimulus depends on its relevance to a feature distinguishing the target from nontargets. Gibson and Kelsey (1998) extended Folk et al.'s (1992) hypothesis by demonstrating that features associated with the appearance of the target display also mediate capture. Although similar to Folk et al. (1992), Gibson and Kelsey's displaywide contingent orienting hypothesis makes it difficult to demonstrate stimulus-driven capture, because an observer must always use some perceptible feature as a signal of the target display's appearance; hence, such features could always be mediating capture. The present article reviews and applies the logic of Gibson and Kelsey's and Folk et al.'s (1992) hypotheses to experiments from the attentional capture literature, and assesses whether previously reported capture effects were mediated by top-down attentional control. It concludes that these capture effects were not stimulus-driven.

The time course of intended and unintended allocation of attention

According to the contingent involuntary orienting hypothesis, only stimuli that match the attentional control settings based on intentions capture attention. In contrast, the surprise-capture hypothesis states that expectancy-discrepant stimuli can capture attention even if they do not match the control settings, implying unintended capture. The purpose of this study is to investigate whether unintended and intended attentional shifts are characterized by different time courses, indicating different underlying mechanisms. An unintended attentional shift was tested by the first, unannounced presentation of a color singleton at the location of a visual search target, and intended shifts by the following repeated presentations of a predictive singleton. Differences in time course were revealed by varying the stimulus onset asynchrony (SOA) between singleton and target. Results showed that accuracy with expected singletons was barely affected by SOA, whereas SOA strongly affected accuracy with the unexpected singleton. The results are interpreted as supporting the surprise-capture hypothesis. It is furthermore argued that a division of labor between contingent capture and surprise in the control of attention supports adaptive behavior.

Attentional capture by auto- and allo-cues

In a host of studies, the ability of various types of cues to capture attention has been examined. This article reviews a number of these studies by organizing them into a classification scheme based on the relationship between the putative attention-capturing item (the cue) and the item used to assess the distribution of attention (the probe). The second dimension of this taxonomy divides paradigms of attentional capture into those in which capture is indexed by performance benefits and those in which capture is indexed by performance costs. The relative methodological merits and disadvantages of the paradigms that occupy each of the cells of the resulting two-by-two matrix are discussed. A final section offers a new interpretation of the finding that dynamic cues capture attention.

Goal-driven modulation of stimulus-driven attentional capture in multiple-cue displays

Six location-cuing experiments were conducted to examine the goal-driven control of attentional capture in multiple-cue displays. In most of the experiments, the cue display consisted of the simultaneous presentation of a red direct cue that was highly predictive of the target location (the unique cue) and three gray direct cues (the standard cues) that were not predictive of the location. The results indicated that although target responses were faster at all cued locations relative to uncued locations, they were significantly faster at the unique-cue location than at the standard-cue locations. Other results suggest that the faster responses produced by direct cues may be associated with two different components: an attention-related component that can be modulated by goal-driven factors and a nonattentional component that occurs in parallel at multiple direct-cue locations and is minimally affected by the same goal-driven factors.

When something old becomes something new: spatiotemporal object continuity and attentional capture

This article examines the possibility that the visal system treats dynamic cues a instances of new perceptual objects undersome circumstances. Using the contingent capture paradigm (C. L. Folk, R. W. Remington, & J. C. Johnston, 1992), the author compared luminance change cues of different magnitude for their ability to capture attention when participants were set for new objects. Wheras small luminance changes failed to produce attentional capture, large luminance changs indeed captured attention, suggesting that they were treated as compatible with the participants' attentional set for new objects. It is argued that sufficiently large luminance transients led to a disurption of spatiotemporal object continuity and precipitated the emergence of a new perceptual object.

Evidence for attentional capture by a surprising color singleton in visual search

Three experiments were conducted to investigate whether surprising color singletons capture attention. Participants performed a visual search task in which a target letter had to be detected among distractor letters. Experiments 1 and 2 assessed accuracy as the dependent variable. In Experiment 1, the unannounced presentation of a color singleton 500 ms prior to the letters (and in the same position as the target letter) resulted in better performance than in the preceding conjunction search segment, in which no singleton was presented, and performance was as good in this surprise-singleton trial as in the following feature search segment, in which the singleton always coincided with the target. In contrast, no improvement was observed when the color singleton was presented simultaneously with the letters in Experiment 2, indicating that attentional capture occurred later in the surprise trial than in the feature search segment. In Experiment 3, set size was varied, and reaction time was the dependent variable. Reaction time depended on set size in the conjunction search segment, but not in the surprise trial nor in the feature search segment. The results of the three experiments support the view that surprising color singletons capture attention independently of a corresponding attentional set.

Attention shifts to salient targets

To investigate the role of salience in fast visual search, time courses for the detection and identification of salient targets were measured in six subjects, using texture-like line arrays. Single lines were made salient from luminance contrast, motion contrast, or by an added circular cue that is known to attract focal attention. Three major findings are reported: (1) Identification of target orientation required longer presentations than detection of the saliency effect itself, consistent with the model that target salience attracts focal attention for target analysis. (2) Different saliency mechanisms produced similar effects, suggesting that salience from feature contrast is functionally equivalent to salience evoked from a visual cue. (3) Circular cues were most effective when presented close to the target; performance in target identification decreased when the diameter was enlarged so that the cue was presented farther away and on a different spatial scale. All together, these findings suggest that popout targets in visual search may be detected fast and independent of set size because (a) they are salient and attract focal attention, and (b) their salience is produced on the same spatial scale and at the same location in the visual field where target properties are encoded.

Attentional capture with various distractor and target types

Effects of nonpredictive distractors that involved changes in luminance, size, or shape were examined in three experiments. In Experiment 1, with two types of distractors (onsets and offsets), accuracy was better on trials when the distractor was near the location of either an offset or an onset target than on trials when the distractor was in a different location from that of the target, demonstrating attentional capture. Capture occurred both when the type of target (onset or offset) was blocked and therefore predictable and also when the type of target was mixed within blocks and therefore not predictable. Further experiments indicated that distractors captured attention even when the change to distractor did not create a new perceptual object. Neither a singleton-detection mode, nor a contingent involuntary orienting hypothesis, nor creation of a new object seems to explain all of these data adequately. Rather, capture may depend on a number of factors in the task.

Selective attention in animal discrimination learning

The traditional approach to the study of selective attention in animal discrimination learning has been to ask if animals are capable of the central selective processing of stimuli, such that certain aspects of the discriminative stimuli are partially or wholly ignored while their relationships to each other, or other relevant stimuli, are processed. A notable characteristic of this research has been that procedures involve the acquisition of discriminations, and the issue of concern is whether learning is selectively determined by the stimulus dimension defined by the discriminative stimuli. Although there is support for this kind of selective attention, in many cases, simpler nonattentional accounts are sufficient to explain the results. An alternative approach involves procedures more similar to those used in human information-processing research. When selective attention is studied in humans, it generally involves the steady state performance of tasks for which there is limited time allowed for stimulus input and a relatively large amount of relevant information to be processed; thus, attention must be selective or divided. When this approach is applied to animals and alternative accounts have been ruled out, stronger evidence for selective or divided attention in animals has been found. Similar processes are thought to be involved when animals search more natural environments for targets. Finally, an attempt is made to distinguish these top-down attentional processes from more automatic preattentional processes that have been studied in humans and other animals.

Attention effects of abrupt-onset precues with central, single-element, and multiple-element precues

Endogenous and exogenous processes of attention have been inferred with different types of precues used in allocation of attention to a target location. In the present research, a comparison was made between the typical peripheral single-element precue (SEP), a central precue, and a multiple-element precue (MEP) in order to further understanding of the processes involved in allocation of attention. Two precues were used on each trial in these experiments. An abrupt-onset precue appeared with an SEP, an MEP, or a central precue and was followed 50 or 300 ms later by a screen containing a target and two distractor characters. The abrupt-onset precue and the other precue each could be valid or invalid in indicating the location of the target, as in the study by Juola, Koshino, and Warner (1995). Response times to the targets showed that validity effects of the abrupt-onset precue and the MEP or central precue were additive, whereas those of the abrupt-onset precue and the SEP were interactive. These data suggest that, like a central precue, an MEP is an endogenous precue that guides conscious control of attention and has its attentional effects at a different processing level from an SEP, which is an exogenous precue and may compete for attentional resources with an abrupt-onset precue.