Resolving conflicting views: Gaze and arrow cues do not trigger rapid reflexive shifts of attention

It has become widely accepted that the direction of another individual's eye gaze induces rapid, automatic, attentional orienting, due to it being such a vital cue as to where in our environment we should attend. This automatic orienting has also been associated with the directional-arrow cues used in studies of spatial attention. Here, we present evidence that the response-time cueing effects reported for spatially nonpredictive gaze and arrow cues are not the result of rapid, automatic shifts of attention. For both cue types, response-time effects were observed only for long-duration cue and target stimuli that overlapped temporally, were largest when the cues were presented simultaneously with the response-relevant target, and were driven by a slowing of responses for invalidly cued targets rather than speeding for validly cued ones. These results argue against automatic attention-orienting accounts and support a novel spatial-incongruency explanation for a whole class of rapid behavioural cueing effects.     

Timing of reflexive visuospatial orienting in young, young-old, and old-old adults

This study examined adult age differences in reflexive orienting to two types of uninformative spatial cues: central arrows and peripheral onsets. In two experiments using a Posner cuing task, young adults (ages 18–28 years), young-old adults (60–74 years), and old-old adults (75–92 years) responded to targets that were preceded 100–1,000 ms earlier by a central arrow or a peripheral abrupt onset. In Experiment 1, the cue remained present upon target onset. Facilitation effects at short cue–target stimulus onset asynchronies (SOAs) were prolonged in duration for the two older groups relative to the young adults. At longer cue–target SOAs, inhibition of return (IOR) that was initiated by peripheral onset cues was observed in the performance of young adults but not in that of the two older groups. In Experiment 2, the cue was presented briefly and removed prior to target onset. The change in cue duration minimized age differences (particularly for young-old adults) in facilitation effects and led to IOR for all three age groups. The findings are consistent with the idea that attentional control settings change with age, with higher settings for older adults leading to delayed disengagement from spatial cues.     

Automatic attentional orienting to other people’s gaze in schizophrenia

Explicit tests of social cognition have revealed pervasive deficits in schizophrenia. Less is known of automatic social cognition in schizophrenia. We used a spatial orienting task to investigate automatic shifts of attention cued by another person’s eye gaze in 29 patients and 28 controls. Central photographic images of a face with eyes shifted left or right, or looking straight ahead, preceded targets that appeared left or right of the cue. To examine automatic effects, cue direction was non-predictive of target location. Cue–target intervals were 100, 300, and 800?ms. In non-social control trials, arrows replaced eye-gaze cues. Both groups showed automatic attentional orienting indexed by faster reaction times (RTs) when arrows were congruent with target location across all cue–target intervals. Similar congruency effects were seen for eye-shift cues at 300 and 800?ms intervals, but patients showed significantly larger congruency effects at 800?ms, which were driven by delayed responses to incongruent target locations. At short 100-ms cue–target intervals, neither group showed faster RTs for congruent than for incongruent eye-shift cues, but patients were significantly slower to detect targets after direct-gaze cues. These findings conflict with previous studies using schematic line drawings of eye-shifts that have found automatic attentional orienting to be reduced in schizophrenia. Instead, our data indicate that patients display abnormalities in responding to gaze direction at various stages of gaze processing—reflected by a stronger preferential capture of attention by another person’s direct eye contact at initial stages of gaze processing and difficulties disengaging from a gazed-at location once shared attention is established.     

Reflexive orienting to gaze is not luminance dependent

In the investigation of reflexive orienting to cues, two major theories have emerged: One proposes that transients created by the cue trigger attentional shifts, whereas the other argues that object changes are responsible for instigating orienting. In the present study, we examined whether luminance transients produced by the cue can generate reflexive orienting to gaze. Using a temporal order judgment paradigm under luminant or subjectively equiluminant conditions, participants judged which of two peripheral targets onset first. An uninformative gaze cue served to reflexively shift attention toward one object location, thereby temporally prioritizing the target presented there. The results revealed that attention was successfully shifted toward the cued object, as was evidenced by the participants’ selecting the cued object as appearing first significantly more often than the uncued object, even when the two onset simultaneously. Critically, the results were comparable across luminance conditions. Our findings reveal that luminance transients are not necessary for triggering orienting to gaze cues. We suggest that the orienting observed here can be better explained via an object-based hypothesis whereby object changes, not transients, trigger reflexive orienting.     

Spatial orienting of attention in stereo depth

The aim of this study was to investigate the spatial orienting of visual attention in depth under purely stereoscopic viewing conditions. Random-dot stereograms were used to present disparity-defined target stimuli that were either validly or invalidly cued in depth. In separate tasks, participants responded either to the relative depth of the target (protruding vs. receding) or to its shape (square vs. diamond). Stimulus onset asynchronies (SOAs) between an uninformative exogenous cue and target were varied from 250 to 600?ms. For both tasks, mean response times (RTs) were shorter for validly than invalidly cued target depths and this RT advantage was essentially restricted to the shortest SOA of 250?ms. These results indicate that attention can be reflexively allocated to locations in stereo depth under conditions of low perceptual load, and independent of whether depth is relevant to the task or not.     

On the uniqueness of attentional capture by uninformative gaze cues: facilitation interacts with the Simon effect and is rarely followed by IOR.

Orienting to an uninformative peripheral cue is characterized by a brief facilitation followed by a long-lasting inhibition once attention is removed from the cued location. Although central gaze cues cause reflexive orienting, the inhibitory effect that is relatively ubiquitous following exogenous orienting to uninformative peripheral cues has been relatively rare. We hypothesized that IOR might be seen following gaze-induced orienting if attention were effectively returned to centre by a return gaze or return flash. The timecourse of gaze-directed orienting was measured by varying the interval between the gaze cue and a peripheral target requiring an orientation discrimination (permitting measurement of the Simon effect). Significant facilitation was observed at all but the longest SOA tested, 2,880 ms, by which time the facilitation had disappeared with no evidence of IOR. Gaze-induced cuing (which was unaffected by return cue condition) interacted with the Simon effect, decreasing it at the gazed-at location, a pattern that is not seen with more typical endogenous and exogenous cuing.     

Investigating hemispheric lateralization of reflexive attention to gaze and arrow cues

Recent studies have demonstrated that central cues, such as eyes and arrows, reflexively trigger attentional shifts. However, it is not clear whether the attentional mechanisms induced by these two cues are similar or rather differ in some important way. We investigated hemispheric lateralization of the orienting effects induced by the two cue types in a group of 48 healthy participants comparing arrows and eye gaze as central non-predictive cues in a discrimination task, in which a target stimulus was briefly presented in one of two peripheral positions (left or right of fixation). As predicted by neuropsychological data, reflexive orienting to gaze cues was only observed when the target was presented in the left visual field, whereas reflexive orienting to arrow cues occurred for targets presented in both left and right visual fields.     

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.     

Spatial cueing by social versus nonsocial directional signals

A cost-benefit analysis was used to investigate whether reflexive effects in a spatial cueing task are stronger when target location is cued by another person's gaze rather than arrows because the relative contribution of attentional shifts versus automatic priming is greater in the case of gaze cues. Across four experiments, nonpredictive arrows triggered rapid facilitatory, inhibition-less priming that peaked at 300-500ms SOA and then died away; across three experiments, nonpredictive gaze cues triggered facilitation-plus-costs at SOAs of 300-400ms or more, suggesting that gaze cues trigger stronger (and longer) attentional effects. At 200 ms SOA, gaze cues triggered facilitation-without-cost, consistent with the view that facilitatory effects accrue more rapidly due to earlier automatic priming, whereas costs are manifest slightly later, when attentional effects come online. There was some evidence that nonpredictive gaze cues trigger long-lasting congruency effects so long as observers maintain their preparedness to respond. Findings support the view that gaze is a unique symbolic directional cue.     

Inhibition of return in response to gaze cues: The roles of time course and fixation cue

Recent studies have demonstrated that orienting of attention in response to nonpredictive gaze cues arises rapidly and automatically, in a similar fashion to peripheral sudden onset cueing. However, while peripheral cues consistently elicit inhibition of return (IOR) at about 300 ms following cue onset, very little is known about inhibition effects in response to gaze cues. The present experiments systematically examined the conditions under which IOR arises with such cues. Reliable inhibition effects were obtained. Importantly, IOR emerged only at long cue-target intervals and only when a second cue actively triggered attention away from the cued location. This suggests that compared to sudden onset cueing, gaze cueing results in both prolonged facilitation and a delayed onset of inhibition processes. Thus, although both types of cues elicit very similar orienting effects in terms of their basic behavioural outcomes, there are more subtle differences between gaze and peripheral cues with respect to the maintenance and quality of those cueing effects across time.     

Eye gaze versus arrows as spatial cues: two qualitatively different modes of attentional selection

This study aimed to evaluate the type of attentional selection (location- and/or object-based) triggered by two different types of central noninformative cues: eye gaze and arrows. Two rectangular objects were presented in the visual field, and subjects' attention was directed to the end of a rectangle via the observation of noninformative directional arrows or eye gaze. Similar experiments with peripheral cues have shown an object-based effect: faster target identification when the target is presented on the cued object as compared to the uncued object, even when the distance between target and cue was the same. The three reported experiments aimed to compare the location- and object-based attentional orienting observed with arrows and eye gaze, in order to dissociate the orienting mechanisms underlying the two types of orienting cues. Results showed similar cueing effects on the cued versus oppositely cued locations for the two cue types, replicating several studies with nonpredictive gaze and arrow cues. However, a pure object-based effect occurred only when an arrow cue was presented, whereas a pure location-based effect was only found for eye-gaze cues. It is suggested that attention is nonspecifically directed to nearby objects when a noninformative arrow is used as cue, whereas it is selectively directed to a specific cued location when noninformative eye gaze is used. This may be mediated by theory of mind mechanisms.     

Searching for inhibition of return in the rat using the covert orienting of attention task

Inhibition of return (IOR) is an important psychological construct describing inhibited responses to previously attended locations. In humans, it is investigated using Posner’s cueing paradigm. This paradigm requires central visual fixation and detection of cued stimuli to the left or right of the fixation point. Stimuli can be validly or invalidly cued, appearing in the same or opposite location to the cue. Although a rat version of the spatial cueing paradigm (the covert orienting of attention task) does exist, IOR has so far not been demonstrated. We therefore investigated whether IOR could be robustly demonstrated in adult male rats using the covert orienting of attention task. This task is conducted in holed wall operant chambers with the central three holes mimicking the set-up for Posner cueing. Across four samples of rats (overall n = 84), we manipulated the following task parameters: stimulus onset asynchronies (Experiments 1–3), cue brightness (Experiment 1b) and the presence of a central reorienting event (Experiment 4). In Experiment 1, we also investigated strain differences by comparing Lister Hooded rats to Sprague–Dawley rats. Although Lister Hooded rats briefly showed evidence of IOR (Experiment 1a, and see Online Resource 1 data), we were unable to replicate this finding in our other experiments using different samples of this strain. Taken together, our findings suggest that IOR cannot be robustly demonstrated in the rat using the covert orienting of attention task conducted in holed wall operant chambers.     

ERPs reveal similar effects of social gaze orienting and voluntary attention, and distinguish each from reflexive attention

Spatial attention can be reflexively captured by a physically salient stimulus, effortfully directed toward a relevant location, or involuntarily oriented in the direction of another person's gaze (i.e., social gaze orienting). Here, we used event-related potentials to compare the effects of these three types of orienting on multiple stages of subsequent target processing. Although gaze orienting has been associated more strongly with reflexive capture than with voluntary attention, the present data provide new evidence that the neural effects of social gaze orienting are markedly different from the effects of reflexive attentional capture by physically salient stimuli. Specifically, despite their similar behavioral effects, social gaze orienting and reflexive capture produce different effects on both early sensory processing (~120 ms; P1/N1 components) and later, higher-order processing (~300 ms; P3 component). In contrast, the effects of social gaze orienting were highly similar to those of voluntary orienting at these stages of target processing.     

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.     

Attentional shifts to emotionally charged cues: Behavioural and erp data

Abstract

When information activated in memory involves emotional associations, the ability to shift attention away from an emotional cue is impaired compared to an emotionally neutral cue. The purpose of the present study was to investigate how emotional stimuli modulate attentional processes, and how this is reflected in localised brain electrical activity. Eight emotion and eight neutral words served as cues in a covert attention spatial orienting task. The cues were either valid or invalid indicators of which hemifield the target would be presented to. In the remaining trials, no cue was presented prior to the target. Twenty subjects were instructed to manually respond to the target as fast as possible. Event-related potentials (ERPs) showed an enhanced P3 component to the emotion words. The ERPs to the target showed enhanced P1 and P3 components on invalid trials, with emotional cues. There were faster reaction times (RTs) to validly cued targets, but only when the emotion words served as cues. The results demonstrated that the emotional cues elicited sustained focused attention, facilitating an engage mechanism of spatial orienting.     

The owl and the pussycat: Gaze cues and visuospatial orienting

Recent research has shown that nonpredictive gaze cues trigger reflexive shifts in attention toward the looked-at location. But just how generalizable is this spatial cuing effect? In particular, are people especially tuned to gaze cues provided by conspecifics, or can comparable shifts in visual attention be triggered by other cue providers and directional cues? To investigate these issues, we used a standard cuing paradigm to compare the attentional orienting produced by different cue providers (i.e., animate vs. inanimate) and directional cues (i.e., eyes vs. arrows). The results of three experiments revealed that attentional orienting was insensitive to both the identity of the cue provider and the nature of the triggering cue. However, compared with arrows, gaze cues prompted a general enhancement in the efficiency of processing operations. We consider the implications of these findings for accounts of reflexive visual orienting.     

Object-based attentional effects in response to eye-gaze and arrow cues

Recent studies have demonstrated that central cues, such as eyes and arrows, reflexively trigger attentional shifts. However, it is not clear whether the attention induced by these two cues can be attached to objects within the visual scene. In the current study, subjects' attention was directed to one of two objects (square outlines) via the observation of uninformative directional arrows or eye gaze. Then, the objects rotated 90° clockwise or counter-clockwise to a new location and the target stimulus was presented within one of these two objects. Results showed that independent of the cue type participants responded faster to targets in the cued object than to those in the uncued object. This suggests that in dynamic displays, both gaze and arrow cues are able to trigger reflexive shifts of attention to objects moving within the visual scene.     

The influence of a salience distinction between bilateral cues on the latency of target‐detection saccades

The spatial cueing paradigm, with saccades to targets as the method of response, was used to investigate the influence of two simultaneously presented cues on the orienting of visual attention. Participants were presented with bilateral cues, one of which was perceptually salient (high luminance) relative to the other. They participated in one of three conditions: in the ‘bright side likely’ condition targets usually (p = .8) appeared near the more salient cue; in the ‘dim side likely’ condition targets usually (p = .8) appeared near the less salient cue; and in the ‘neutral’ condition the arrangement of the cues was uninformative with respect to target location. Brief SOAs (0, 50, 100 and 150 ms) were employed. Rapid reflexive orienting to the more salient stimulus was observed in the neutral condition: saccadic latencies were faster when the target appeared near the bright cue, and this was found even across the two shortest SOAs. However, this reflexive orienting was suppressed in both the bright side likely and dim side likely conditions: the advantage observed at the bright cue's location across the two shortest SOAs in the neutral condition was significantly attenuated in the two contingent conditions. Results point to rapid expectancy‐based interference in the reflexive process of attention capture.     

Implied body action directs spatial attention

Research confirms that the body influences perception, but little is known about the embodiment of attention. We investigated whether the implied actions of others direct spatial attention, using a lateralized covert-orienting task with nonpredictive central cues depicting static, right/left-facing bodies poised in midaction. Validity effects (decreased response times for validly compared with invalidly cued trials) indicated orienting in the direction of the implied action. In Experiment 1, we compared action (running, throwing) with nonaction (standing) cues. Only the action cues produced validity effects, suggesting that implied action directs attention. The action cues produced faster responses overall, suggesting that action cues prime motor responses. In Experiment 2, we determined whether action cues shifted attention in a specific direction rather than to a general side of space: Two cues had similar action speed and motor effort but differed in implied direction (jumping, vertical; throwing, horizontal). Validity effects were found only for the throw cues for which the implied motion direction was consistent with lateralized target locations. In Experiment 3, we compared block-like stimuli to the throwing action stimuli to examine whether lower level perceptual information could account for the attention effects alone. Validity effects were found only for the human-action stimuli. Overall, the results suggest that predictive simulations of action shift attention in action-consistent directions.     

Arrow-elicited cueing effects at short intervals: Rapid attentional orienting or cue-target stimulus conflict?

The observation of cueing effects (faster responses for cued than uncued targets) rapidly following centrally-presented arrows has led to the suggestion that arrows trigger rapid automatic shifts of spatial attention. However, these effects have primarily been observed during easy target-detection tasks when both cue and target remain on the screen until the behavioral response. We manipulated stimulus duration and task difficulty in an attention-cueing experiment to explore non-attentional explanations for rapid cueing effects. Contrary to attention-based predictions, short-interval cueing effects were observed only for long-duration cue and target stimuli, occurred even when the cue and target were presented simultaneously, and were driven by slowing of the uncued-target responses, rather than any facilitation for cued targets. We propose that, under these long-duration, short-interval conditions, the processing of the cue and target interact more extensively in the brain, and that when the cue and target convey incongruent spatial information (i.e., on invalidly cued trials) it leads to conflict-related slowing of responses.