The neural correlates of orienting to walking direction in 6‐month‐old infants: An ERP study

The ability to detect social signals represents a first step to enter our social world. Behavioral evidence has demonstrated that 6‐month‐old infants are able to orient their attention toward the position indicated by walking direction, showing faster orienting responses toward stimuli cued by the direction of motion than toward uncued stimuli. The present study investigated the neural mechanisms underpinning this attentional priming effect by using a spatial cueing paradigm and recording EEG (Geodesic System 128 channels) from 6‐month‐old infants. Infants were presented with a central point‐light walker followed by a single peripheral target. The target appeared randomly at a position either congruent or incongruent with the walking direction of the cue. We examined infants' target‐locked event‐related potential (ERP) responses and we used cortical source analysis to explore which brain regions gave rise to the ERP responses. The P1 component and saccade latencies toward the peripheral target were modulated by the congruency between the walking direction of the cue and the position of the target. Infants' saccade latencies were faster in response to targets appearing at congruent spatial locations. The P1 component was larger in response to congruent than to incongruent targets and a similar congruency effect was found with cortical source analysis in the parahippocampal gyrus and the anterior fusiform gyrus. Overall, these findings suggest that a type of biological motion like the one of a vertebrate walking on the legs can trigger covert orienting of attention in 6‐month‐old infants, enabling enhancement of neural activity related to visual processing of potentially relevant information as well as a facilitation of oculomotor responses to stimuli appearing at the attended location.     

Modulation of the Spatial Extent of the Attentional Focus in High-level Volleyball Players

In this study, we explored the ability of first league professional volleyball players to modulate the allocation of attentional resources in the visual space by adapting the size of the attentional focus. Like Castiello and Umilta (1990), we employed an experimental procedure that is a variation of Posner's (1980) paradigm for exploring covert orienting of visuospatial attention. In a signalled reaction time task, a peripheral cue of varying size was presented unilaterally or bilaterally of a central fixation point, followed by a target at different stimulus onset asynchronies. The target could occur validly inside the cue or invalidly outside it with varying spatial relation to its boundary. Our results suggest that volleyball players are better able than controls to modulate the distribution of attentional resources within and around peripherally cued areas. Moreover, volleyball players seem to be able to flexibly adapt the gradient of attentional resources around the cued area, as would be expected from their sport practice.     

The development of attentional orienting during the school‐age years

This study was designed to assess the development of spatial attentional orienting during the school‐age years. To that end, we used a cost‐benefit attentional cueing task with short (100 ms) and long (800 ms) cue‐to‐target intervals to examine attentional processing independent of motor skills and perceptual processing in 200 7–17‐year‐olds and 40 adults. We found that orienting attention, disengaging attention and visual processing in an unattended location, were all progressively more accurate and faster with increasing age. Our data thus suggest that the efficiency of attentional orienting improves in an age‐related manner throughout the school‐age years.     

Effects of informative peripheral cues on eye movements: Revisiting William James’ “derived attention”

Two experiments examined effects of peripheral information on the latency of saccadic eye movements. In Experiment 1, simple target stimuli were presented to the left or right visual field. Prior to each target, a pair of cue letters was presented for 40msec bilaterally. The relative location of the letters (W-S or S-W) was related to target location, but participants were not informed of this contingency. After a brief practice period, saccadic latencies were faster for targets at the likely location, as indicated by the letter pair. This derived peripheral cueing effect was related to participants' awareness of the relation between cue type and target location. Experiments 2A and 2B employed monocular viewing in order to compare performance across the nasal and temporal visual fields. The effect observed in Experiment 1 was confined to the nasal visual field. In a reflexive orienting condition, the effect of a unilateral letter cue was larger in the temporal visual field. It is concluded that the neurocognitive processes responsible for derived peripheral cueing are distinct from those involved in either reflexive or voluntary orienting.     

A perceptual–attentional explanation of gaze following in 3‐ and 6‐month‐olds

Two experiments were conducted with 3‐ and 6‐month‐olds using a standard gaze following procedure with targets to examine the possibility that perceptual–attentional constraints may affect young infants’ gaze following. In Experiment 1, either moving or stationary targets were positioned at 15° from the infants’ midline. In Experiment 2, stationary targets were positioned at either 25° or 40° from the infants’ midline. Gaze following was evaluated with three criteria. Infants made significantly more correct responses to the 15° stationary targets than all other response types combined. When targets were moving or further away, infants made significantly more correct than incorrect responses when they made a turn; however, they did not make significantly more correct responses across all trials. It is argued that the infants’ responses are indicative of perceptual–attention constraints operating where the adult head and eye turn shifts infants’ attention to the side but whether the infants then ‘gaze follow’ depends on the structure of the environment as well as the infants’ ability to disengage attention and initiate saccadic eye movements.     

Visual attention in adolescents: Facilitating effects of sport expertise and acute physical exercise

ObjectivesThis study investigated visual attention of adolescent orienteers and physically active adolescents non-practising orienteering both at rest and under acute sub-maximal exercise. It was verified whether the practice of orienteering facilitates the development of visual attentional abilities and whether orienteers, who are used to simultaneously handle physiological and cognitive-attentional loads, may better profit than non-orienteers from the beneficial effects of sub-maximal physical load on processing speed.MethodsBoth the focusing of attention at foveal and parafoveal locations and the orienting of attention at peripheral locations were investigated. In two discriminative reaction time (RT) experiments, a cue of varying size was presented centrally or peripherally and followed by a compound stimulus with local and global target features. The stimulus-onset asynchrony (SOA) varied between a short and a long interval.ResultsIn both experiments, adolescent orienteers and non-practisers showed different patterns of attentional effects. Adolescent orienteers were more similar to young adults in the attentional performance, being better able than non-practisers to perform complex attentional operations involving the intentional zooming of attention in the central visual field and the orienting of the attentional focus in the peripheral visual field. Also, both orienteers and non-orienteers speeded up their performance during exercise, but this facilitation effect was more pronounced for orienteers, who are probably skilled in directing the available resources to task demands.ConclusionsOur results suggest that cognitive expertise represents a key factor in sports that accelerates the development of visual attention and enhances the facilitating effects of physical exercise on attentional performance.     

Time‐of‐day variation of visuo‐spatial attention

Time‐of‐day variation of visuo‐spatial attention in relation to body temperature and subjective arousal was assessed. At five different times of day, alertness, covert, and overt orienting of attention were assessed in fifteen healthy subjects. Based on previous studies reporting a tight coupling of alerting and orienting the present study investigates potential attentional asymmetries induced by diurnal variations of arousal. Both covert and overt orienting of attention improved in the course of the day. However, no asymmetries between left and right visual hemifields could be detected. Covert orienting additionally covaried with body temperature, indicating a quite close relation between the attentional arousal and orienting system. Conversely, overt orienting only improved due to repeated testing but did not correlate with body temperature suggesting a partial independence of both modes of attentional orienting. It can be assumed that due to limited diurnal variations of arousal in the participants and practice effects caused by repeated testing, no attentional asymmetries could be provoked.     

A developmental study of covert orienting to peripheral visual cues

Observers aged 6, 8, and 20 years participated in a speeded classification task designed to measure covert shifts of visual attention. On each trial observers responded to a target which appeared in one of three locations arrayed horizontally across the display. Three prestimulus cues were employed: neutral (the cue was present in all three possible target locations), unpredictable (the cue was present in the target location on a random basis), and predictable (the cue was present in the target location on 80% of the trials). There were four developmental findings: (1) Observers of all ages oriented attention automatically to the cued locations, (2) children processed targets in non-cued locations more slowly than adults, (3) only adults took advantage of the predictability of the cue, and (4) all age groups provided evidence that strategic orienting competes with response priming for cognitive resources. The implications of these findings for theories of attentional development are discussed.     

Contrast polarity of eyes modulates gaze‐cueing effect1

Two experiments using a modified Posner‐type visual cueing paradigm tested the prediction that detecting the darker region of the eyes of another's gaze triggers a reflexive orienting of the observer in the direction of the gaze. A target was presented in the left or right visual‐field following a gaze‐cue with positive or negative‐image polarity (Experiment 1). In Experiment 2, the polarity of the eyes was manipulated independently of the negative polarity of the face (eye‐positive or eye‐negative‐image polarity conditions). The results showed that the response to the target presented at the side the eyes gazed toward was faster than for the target presented at the other side in the positive polarity condition (Experiment 1), whereas, in the negative polarity condition, the gaze‐cuing effect was not found. In Experiment 2, in the eye‐negative condition, a reversed gaze‐cueing effect appeared, whereas in the eye‐positive polarity condition, a typical gaze‐cueing effect was obtained. These findings suggested that the reflexive orienting of the observer shifts toward the position indicated by the darker region of the other's eyes.     

Oculomotor readiness and covert orienting: differences between central and peripheral precues.

The costs produced by invalid precues can depend on the spatial relationship between the cued location and the target location. If oculomotor programs mediate attention shifts, then the effect of varying the spatial relation between the cue and target should be the same for covert orienting (indexed by manual responses) and saccadic responses. We found this to be true only for central precues. With central precues, both manual and saccadic costs were greater when cue and target occurred on opposite sides of the vertical meridian than when they occurred on the same side. With peripheral precues, there were no meridian effects in either response condition, but there was a significant dissociation in the pattern of saccadic and manual costs. For manual responses costs were greater when the target was eccentric relative to the cue, whereas for saccades costs were greater when the cue was eccentric to the target. These results provide additional support for the idea that different orienting mechanisms are engaged by central and peripheral precues. They further suggest that the relationship between oculomotor and attentional orienting may depend on the nature of the precue, with the potential for interdependence being greater with central precues.     

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.     

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.     

Oculomotor readiness and covert orienting: Differences between central and peripheral precues

The costs produced by invalid precues can depend on the spatial relationship between the cued location and the target location. If oculomotor programs mediate attention shifts, then the effect of varying the spatial relation between the cue and target should be the same for covert orienting (indexed by manual responses) and saccadic responses. We found this to be true only for central precues. With central precues, both manual and saccadic costs were greater when cue and target occurred on opposite sides of the vertical meridian than when they occurred on the same side. With peripheral precues, there were no meridian effects in either response condition, but there was a significant dissociation in the pattern of saccadic and manual costs. For manual responses costs were greater when the target was eccentric relative to the cue, whereas for saccades costs were greater when the cue was eccentric to the target. These results provide additional support for the idea that different orienting mechanisms are engaged by central and peripheral precues. They further suggest that the relationship between oculomotor and attentional orienting may depend on the nature of the precue, with the potential for interdependence being greater with central precues.     

Visual orienting in response to attentional cues: Spatial correspondence is critical,conscious awareness is not

Three experiments examined visual orienting in response to spatial precues. In Experiments 1 and 2, attentional effects of central letters were stimulus driven: Orienting was dependent on the spatial layout of the cue display. When there were no correspondences between spatial features of the cue display and target location, attentional effects were absent, despite a conscious intention to orient in response to the symbolic information carried by the cue letters. In Experiment 3 clear orienting effects were observed when target location corresponded with spatial features of the cue display, but the magnitude of these effects was unaffected by whether participants were aware or unaware of the cue–target relationship. These findings are consistent with the view that (1) spatial correspondences between cues and targets are a critical factor driving visual orienting in cueing paradigms, and (2) attentional effects of spatial precues are largely independent of participants’ conscious awareness of the cue–target relationship.     

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.     

Face detection in 2‐ to 6‐month‐old infants is influenced by gaze direction and species

Humans detect faces efficiently from a young age. Face detection is critical for infants to identify and learn from relevant social stimuli in their environments. Faces with eye contact are an especially salient stimulus, and attention to the eyes in infancy is linked to the emergence of later sociality. Despite the importance of both of these early social skills—attending to faces and attending to the eyes—surprisingly little is known about how they interact. We used eye tracking to explore whether eye contact influences infants' face detection. Longitudinally, we examined 2‐, 4‐, and 6‐month‐olds' (N = 65) visual scanning of complex image arrays with human and animal faces varying in eye contact and head orientation. Across all ages, infants displayed superior detection of faces with eye contact; however, this effect varied as a function of species and head orientation. Infants were more attentive to human than animal faces and were more sensitive to eye and head orientation for human faces compared to animal faces. Unexpectedly, human faces with both averted heads and eyes received the most attention. This pattern may reflect the early emergence of gaze following—the ability to look where another individual looks—which begins to develop around this age. Infants may be especially interested in averted gaze faces, providing early scaffolding for joint attention. This study represents the first investigation to document infants' attention patterns to faces systematically varying in their attentional states. Together, these findings suggest that infants develop early, specialized functional conspecific face detection.     

Attentional Orienting in Two-dimensional Space

This paper examines how the covert orienting of spatial attention affects motor responses to visual stimuli. Premotor theories, as well as hemi-field inhibition accounts of visual attention predict an increase in response times when a target stimulus appears in the opposite direction to a spatial cue. Some models also suggest that this meridional effect should be increased across oblique meridians. Two types of cue (central and peripheral) were used to orient attention towards locations prior to the onset of visual targets. Simple manual (press button) and saccadic responses were measured. No meridional effects were found with peripheral cues, whereas central cueing produced meridional effects across all meridians. Cueing effects did not vary significantly with two-dimensional axis for either manual or saccadic responses. Increases in response time with cue-target distance were found for both response and cue types. For saccades, distance gradients were shallower moving distally rather than proximally from the cued position. However, simple manual responses did not show this asymmetry. Orienting to central cues also modulated the amplitude of saccades. The results are consistent with an effect of attentional cues in oculomotor centres as well as the existence of actiondependent attentional representations. However, it is proposed that, rather than reflecting oculomotor programming, meridional effects arise from a directional organization within spatio-cognitive representations.     

Top‐down contextual knowledge guides visual attention in infancy

The visual context in which an object or face resides can provide useful top‐down information for guiding attention orienting, object recognition, and visual search. Although infants have demonstrated sensitivity to covariation in spatial arrays, it is presently unclear whether they can use rapidly acquired contextual knowledge to guide attention during visual search. In this eye‐tracking experiment, 6‐ and 10‐month‐old infants searched for a target face hidden among colorful distracter shapes. Targets appeared in Old or New visual contexts, depending on whether the visual search arrays (defined by the spatial configuration, shape and color of component items in the search display) were repeated or newly generated throughout the experiment. Targets in Old contexts appeared in the same location within the same configuration, such that context covaried with target location. Both 6‐ and 10‐month‐olds successfully distinguished between Old and New contexts, exhibiting faster search times, fewer looks at distracters, and more anticipation of targets when contexts repeated. This initial demonstration of contextual cueing effects in infants indicates that they can use top‐down information to facilitate orienting during memory‐guided visual search.     

Allocation of attention in the visual field

This research investigated whether attentional resources can be simultaneously allocated to several locations in a visual display, whether the mode of processing (serial or parallel) can be switched within a trial, and the nature of the costs when attentional resources are concentrated on an invalid location. Subjects were required to determine which of two target letters was present in eight-letter circular displays. In precue conditions, a primary and a secondary target location were designated 150 ms before target onset by an indicator that varied in validity. In the control conditions no cue was provided. A second experiment verified several assumptions that had been made in interpreting the data of Experiment 1. Modifications in Jonides' (1983) two-process model were suggested in terms of a zoom lens model of attentional resources. Instead of two alternative processing modes, attentional resources are conceived as capable of distribution over the visual field, but with low resolving power, or as continuously constricting to small portions of the visual field with a concomitant increase in processing power.     

The effects of spatial uncertainty and cue predictability on visual orienting in children

Visual orienting was studied using a task that required participants to respond to stimuli at various locations that were either accurately or inaccurately cued. Orienting abilities of children ages 6 to 8 years, and young adults (21 years) were tested under conditions of spatial uncertainty (i.e., multiple possible target locations), and variable cue predictability (i.e., variable proportion of validly cued targets). The results indicate that children orient their attentional resources automatically to abrupt visual onsets, and do so under conditions when it is not beneficial to overall performance. Adults, on the other hand, are able to control their orienting in such a way that it is limited to conditions where it improves their task efficiency. There appears to be developmental change in the ability to assess the utility of a location cue and/or to moderate responses in accordance with the utility of a cue. This finding is discussed in terms of the development of attentional control and inhibitory processes in children.