Involuntary attention and identification accuracy

Elements of exogenous attentional cueing preserved during optokinetic motion of the visual scene

Navigating through our environment raises challenges for perception by generating salient background visual motion, and eliciting prominent eye movements to stabilise the retinal image. It remains unclear if exogenous spatial attentional orienting is possible during background motion and the eye movements it causes, and whether this compromises the underlying neural processing. To test this, we combined exogenous orienting, visual scene motion, and EEG. 26 participants viewed a background of moving black and grey bars (optokinetic stimulation). We tested for effects of non-spatially predictive peripheral cueing on visual motion discrimination of a target dot, presented either at the same (valid) or opposite (invalid) location as the preceding cue. Valid cueing decreased reaction times not only when participants kept their gaze fixed on a central point (fixation blocks), but even when there was no fixation point, so that participants performed intensive, repetitive tracking eye movements (eye movements blocks). Overall, manual response reaction times were slower during eye movements. Cueing also produced reliable effects on neural activity on either block, including within the first 120 milliseconds of neural processing of the target. The key pattern with larger ERP amplitudes on invalid versus valid trials showed that the neural substrate of exogenous cueing was highly similar during eye movements or fixation. Exogenous peripheral cueing and its neural correlates are robust against distraction from the moving visual scene, important for perceptual cognition during navigation.

The perceptual enhancement by spatial attention is impaired during the attentional blink

A salient, but task-irrelevant stimulus has long been known to capture attention in an automatic, involuntary manner. However, the automaticity of involuntary attention has recently been challenged. While some studies showed that the effect of involuntary attention depended on top-down attentional resources, other studies did not. To reconcile this conflict, we suggest to consider that attentional effect is not homogenous. Specifically, we hypothesized that the dependence of involuntary attention on top-down attention interacts with the presence/absence of the target location uncertainty and distractor interference. Consistent with this hypothesis, we found that when the attentional resources were depleted, the involuntary attention did not affect the perception of a single target stimulus (Experiment 1). However, when the target was accompanied by multiple distractors, evoking uncertainty regarding the target location, the involuntary attentional effect was observed, regardless of the availability of attentional resource (Experiment 2). This was so, even when the target location was always marked by a response cue, minimizing the target location uncertainty (Experiment 3). These findings provide a reconciliation for the theoretical debate regarding the dependence of involuntary attention on top-down attention and clarifies how perception is modulated by involuntary attention.

Brief time course of trait anxiety-related attentional bias to fear-conditioned stimuli: Evidence from the dual-RSVP task

BACKGROUND AND OBJECTIVES

Attentional bias to threat is a much-studied feature of anxiety; it is typically assessed using response time (RT) tasks such as the dot probe. Findings regarding the time course of attentional bias have been inconsistent, possibly because RT tasks are sensitive to processes downstream of attention.

METHODS

Attentional bias was assessed using an accuracy-based task in which participants detected a single digit in two simultaneous rapid serial visual presentation (RSVP) streams of letters. Before the target, two coloured shapes were presented simultaneously, one in each RSVP stream; one shape had previously been associated with threat through Pavlovian fear conditioning. Attentional bias was indicated wherever participants identified targets in the threat's RSVP stream more accurately than targets in the other RSVP stream.

RESULTS

In 87 unselected undergraduates, trait anxiety only predicted attentional bias when the target was presented immediately following the shapes, i.e. 160 ms later; by 320 ms the bias had disappeared. This suggests attentional bias in anxiety can be extremely brief and transitory.

LIMITATIONS

This initial study utilised an analogue sample, and was unable to physiologically verify the efficacy of the conditioning. The next steps will be to verify these results in a sample of diagnosed anxious patients, and to use alternative threat stimuli.

CONCLUSIONS

The results of studies using response time to assess the time course of attentional bias may partially reflect later processes such as decision making and response preparation. This may limit the efficacy of therapies aiming to retrain attentional biases using response time tasks.

Bias-free double judgment accuracy during spatial attention cueing: performance enhancement from voluntary and involuntary attention

Recent research has demonstrated that involuntary attention improves target identification accuracy for letters using non-predictive peripheral cues, helping to resolve some of the controversy over performance enhancement from involuntary attention. While various cueing studies have demonstrated that their reported cueing effects were not due to response bias to the cue, very few investigations have quantified the extent of any response bias or developed methods of removing bias from observed results in a double judgment accuracy task. We have devised a method to quantify and remove response bias to cued locations in a double judgment accuracy cueing task, revealing the true, unbiased performance enhancement from involuntary and voluntary attention. In a 7-alternative forced choice cueing task using backward masked stimuli to temporally constrain stimulus processing, non-predictive cueing increased target detection and discrimination at cued locations relative to uncued locations even after cue location bias had been corrected.

Inhibition of Return Affects Contrast Sensitivity

Inhibition of return (IOR)—a slow response to targets at recently attended locations, is believed to play an important role in guiding behaviour. In the attention literature it has been shown that attentional capture by an exogenous cue affects contrast sensitivity so that it alters the appearance of low-contrast stimuli. Despite a significant amount of work over the last quarter century on IOR, it is not yet clear whether IOR operates in the same way. In the current study we examined the effect of IOR on contrast sensitivity—a very early, low-level perceptual process. We found in both a detection task and an orientation discrimination task that lower contrast was needed to detect the stimulus (Experiment 1) and determine its orientation (Experiment 2) at the cued location than at the uncued location, at short cue–target delays, while higher contrast was needed at long delays—reflecting IOR. These results clearly demonstrate that IOR affects contrast sensitivity in a similar way as attentional capture does and suggest that IOR increases perceived contrast of an object in the uncued location.

The effects of stimulus-driven competition and task set on involuntary attention

It is well established that involuntary attention—the exogenous capture of attention by salient but task-irrelevant stimuli—can strongly modulate target detection and discrimination performance. There is an ongoing debate, however, about how involuntary attention affects target performance. Some studies suggest that it results from enhanced perception of the target, whereas others indicate instead that it affects decisional stages of information processing. From a review of these studies, we hypothesized that the presence of distractors and task sets are key factors in determining the effect of involuntary attention on target perception. Consistent with this hypothesis, here we found that noninformative cues summoning involuntary attention affected perceptual identification of a target when distractors were present. This cuing effect could not be attributed to reduced target location uncertainty or decision bias. The only condition under which involuntary attention improved target perception in the absence of distractors occurred when observers did not adopt a task set to focus attention on the target location. We conclude that the perceptual effects of involuntary attention depend on distractor interference and the adoption of a task set to resolve such stimulus competition.

Past rewards capture spatial attention and action choices

The desire to increase rewards and minimize punishing events is a powerful driver in behaviour. Here, we assess how the value of a location affects subsequent deployment of goal-directed attention as well as involuntary capture of attention on a trial-to-trial basis. By tracking eye position, we investigated whether the ability of an irrelevant, salient visual stimulus to capture gaze (stimulus-driven attention) is modulated by that location’s previous value. We found that distractors draw attention to them significantly more if they appear at a location previously associated with a reward, even when gazing towards them now leads to punishments. Within the same experiment, it was possible to demonstrate that a location associated with a reward can also bias subsequent goal-directed attention (indexed by action choices) towards it. Moreover, individuals who were vulnerable to being distracted by previous reward history, as indexed by oculomotor capture, were also more likely to direct their actions to those locations when they had a free choice. Even when the number of initial responses was made to be rewarded and punished stimuli were equalized, the effects of previous reward history on both distractibility and action choices remained. Finally, a covert attention task requiring button-press responses rather than overt gaze shifts demonstrated the same pattern of findings. Thus, past rewards can act to modulate both subsequent stimulus-driven as well as goal-directed attention. These findings reveal that there can be surprising short-term costs of using reward cues to regulate behaviour. They show that current valence information, if maintained inappropriately, can have negative subsequent effects, with attention and action choices being vulnerable to capture and bias, mechanisms that are of potential importance in understanding distractibility and abnormal action choices.

Simultaneity and temporal order perception: Different sides of the same coin? Evidence from a visual prior-entry study

Attended stimuli are perceived as occurring earlier than unattended stimuli. This phenomenon of prior entry is usually identified by a shift in the point of subjective simultaneity (PSS) in temporal order judgements (TOJs). According to its traditional psychophysical interpretation, the PSS coincides with the perception of simultaneity. This assumption is, however, questionable. Technically, the PSS represents the temporal interval between two stimuli at which the two alternative TOJs are equally likely. Thus it also seems possible that observers perceive not simultaneity, but uncertainty of temporal order. This possibility is supported by prior-entry studies, which find that perception of simultaneity is not very likely at the PSS. The present study tested the percept at the PSS in prior entry, using peripheral cues to orient attention. We found that manipulating attention caused varying temporal perceptions around the PSS. On some occasions observers perceived the two stimuli as simultaneous, but on others they were simply uncertain about the order in which they had been presented. This finding contradicts the implicit assumption of most models of temporal order perception, that perception of simultaneity inevitably results if temporal order cannot be discriminated.

Capturing spatial attention with multisensory cues: a review

The last 30 years have seen numerous studies demonstrating unimodal and crossmodal spatial cuing effects. However, surprisingly few studies have attempted to investigate whether multisensory cues might be any more effective in capturing a person's spatial attention than unimodal cues. Indeed, until very recently, the consensus view was that multisensory cues were, in fact, no more effective. However, the results of several recent studies have overturned this conclusion, by showing that multisensory cues retain their attention-capturing ability under conditions of perceptual load (i.e., when participants are simultaneously engaged in a concurrent attention-demanding task) while their constituent signals (when presented unimodally) do not. Here we review the empirical literature on multisensory spatial cuing effects and highlight the implications that this research has for the design of more effective warning signals in applied settings.

Crossmodal exogenous orienting improves the accuracy of temporal order judgments

Although many studies have demonstrated that crossmodal exogenous orienting can lead to a facilitation of reaction times, the issue of whether exogenous spatial orienting also affects the accuracy of perceptual judgments has proved to be much more controversial. Here, we examined whether or not exogenous spatial attentional orienting would affect sensitivity in a temporal discrimination task. Participants judged which of the two target letters, presented on either the same or opposite sides, had been presented first. A spatially non-predictive tone was presented 200 ms prior to the onset of the first visual stimulus. In two experiments, we observed improved performance (i.e., a decrease in the just noticeable difference) when the target letters were presented on opposite sides and the auditory cue was presented on the side of the first visual stimulus, even when central fixation was monitored ("Experiment 2"). A shift in the point of subjective simultaneity was also observed in both experiments, indicating 'prior entry' for cued as compared to uncued first target trials. No such JND or PSS effects were observed when the auditory tone was presented after the second visual stimulus ("Experiment 3"), thus confirming the attentional nature of the effects observed. These findings clearly show that the crossmodal exogenous orienting of spatial attention can affect the accuracy of temporal judgments.

Testing whether gaze cues and arrow cues produce reflexive or volitional shifts of attention

It has been suggested that two types of uninformative central cues produce reflexive orienting: gaze and arrow cues. Using the criterion that voluntary shifts of attention facilitate both response speed and perceptual accuracy, whereas reflexive shifts of attention facilitate only response speed (Prinzmetal, McCool, & Park, 2005), we tested whether these cues produce reflexive or volitional shifts of attention. A cued letter discrimination task was used with both gaze (Experiments 1A and 1B) and arrow (Experiments 2A and 2B) cues, in which participants responded to the identity of the target letter. In the response time (respond speed) tasks, participants were asked to respond as quickly as possible to the target; in the accuracy (perceptual quality) tasks, participants were asked to respond as accurately as possible. For both cue types, compatible cues were found to facilitate response speed but not perceptual accuracy, indicating that both gaze and arrow cues generate reflexive shifts in attention.

Voluntary and involuntary attention have different consequences: The effect of perceptual difficulty

We propose that voluntary and involuntary attention affect different mechanisms and have different consequences for performance measured in reaction time. Voluntary attention enhances the perceptual representation whereas involuntary attention affects the tendency to respond to stimuli in one location or another. In a spatial-cueing paradigm, we manipulated perceptual difficulty and compared voluntary and involuntary attention. For the voluntary-attention condition, the spatial cue was predictive of the target location, whereas in the involuntary-attention condition it was not. Increasing perceptual difficulty increased the attention effect with voluntary attention, but decreased it with involuntary attention. Thus voluntary and involuntary attention have different consequences when perceptual difficulty is manipulated and hence are probably caused by different mechanisms.

Voluntary and involuntary attention affect face discrimination differently

Do voluntary (endogenous) and involuntary (exogenous) attention have the same perceptual consequences? Here we used fMRI to examine activity in the fusiform face area (FFA--a region in ventral visual cortex responsive to faces) and frontal-parietal areas (dorsal regions involved in spatial attention) under voluntary and involuntary spatial cueing conditions. The trial and stimulus parameters were identical for both cueing conditions. However, the cue predicted the location of an upcoming target face in the voluntary condition but was nonpredictive in the involuntary condition. The predictable cue condition led to increased activity in the FFA compared to the nonpredictable cue condition. These results show that voluntary attention leads to more activity in areas of the brain associated with face processing than involuntary attention, and they are consistent with differential behavioral effects of attention on recognition-related processes.

Color singleton pop-out does not always poop out: an alternative to visual search

Folk psychology suggests that when an observer views a scene, a unique item will stand out and draw attention to itself. This belief stands in contrast to numerous studies in visual search that have found that a unique target item (e.g., a unique color) is not identified more quickly than a nonunique target. We hypothesized that this finding is the result of task demands of visual search, and that when the task does not involve visual search, uniqueness will pop out. We tested this hypothesis in a task in which observers were presented an array of letters and asked to respond aloud, as quickly as possible, with the identity of any one of the letters. The observers were significantly more likely to respond with a uniquely colored letter than would be expected by chance. In a task in which observers blurt out the first thing that they see, unique pop-out does not poop out.