Spatial attention-related modulation of the N170 by backward masked fearful faces

Facial expressions are a basic form of non-verbal communication that convey important social information to others. The relevancy of this information is highlighted by findings that backward masked facial expressions facilitate spatial attention. This attention effect appears to be mediated through a neural network consisting of the amygdala, anterior cingulate, and visual cortex. However, a direct investigation of the neural time course associated with orienting to such stimuli has yet to be performed. In the current investigation, a backward masked fearful face dot-probe task was performed while ERPs were recorded. Reaction time results suggest that spatial attention is captured by backward masked fearful faces and attention is focused at the location of the fear stimulus. Masked right visual field fearful faces enhanced the N170 amplitudes of contralateral occipito-temporal electrodes. The rapid contralateral N170 enhancement was positively correlated with participants’ behavioral index of spatial attention. Thus, backward masked fearful face-elicited spatial attention facilitates behavior and modulates the early stage of facial processing reflected by the N170.     

The orienting of spatial attention to backward masked fearful faces is associated with variation in the serotonin transporter gene

Threat signals facilitate spatial attention, even when awareness of these signals has been restricted through the use of backward masking. However, unrestricted/unmasked threat cues tend to delay the disengagement of attention, whereas restricted/masked threat facilitates orienting, suggesting different underlying mechanisms. Within the general population, the serotonin transporter gene polymorphism (5HTTLPR) is associated with one's allocation of attention to unmasked threat signals. However, it is unclear to what extent the 5HTTLPR gene may be involved in nonconscious biases to masked threat, and whether or not such biases are driven by facilitated orienting or delayed disengagement. Participants were genotyped and performed a dot-probe task with backward masked fearful and neutral faces. Results indicate that short-allele carriers of the 5HTTLPR gene nonconsciously orient spatial attention to masked fearful faces. On the other hand, homozygous long-allele individuals tended to direct attention away from masked fearful faces. All participants' performance was at chance in a posttask assessment of awareness for the masked faces. The results add to current literature on the 5HTTLPR and attention biases, and suggest that threat signals facilitate the orienting of attention in short-allele carriers of the 5HTTLPR gene even under restricted processing conditions.     

Evidence from the eyes: Threatening postures hold attention

Efficient detection of threat provides obvious survival advantages and has resulted in a fast and accurate threat-detection system. Although beneficial under normal circumstances, this system may become hypersensitive and cause threat-processing abnormalities. Past research has shown that anxious individuals have difficulty disengaging attention from threatening faces, but it is unknown whether other forms of threatening social stimuli also influence attentional orienting. Much like faces, human body postures are salient social stimuli, because they are informative of one’s emotional state and next likely action. Additionally, postures can convey such information in situations in which another’s facial expression is not easily visible. Here we investigated whether there is a threat-specific effect for high-anxious individuals, by measuring the time that it takes the eyes to leave the attended stimulus, a task-irrelevant body posture. The results showed that relative to nonthreating postures, threat-related postures hold attention in anxious individuals, providing further evidence of an anxiety-related attentional bias for threatening information. This is the first study to demonstrate that attentional disengagement from threatening postures is affected by emotional valence in those reporting anxiety.     

The face behind the mask: a developmental study

Faces are a rich and available source of social information, and the representation for faces is robust in adults (i.e. the face detection effect; Purcell & Stewart, 1988). The current study compared the developmental trajectory of the robustness of face perception against the trajectory for a non-face object. Participants (5-35 years old) were presented with rapid (17 and 33 millisecond) presentations of face and house stimuli and were instructed to identify the object category of the stimulus (face or house). There was an interaction between object type and age such that the developmental slope for face identification was steeper than the slope for house identification for the 17-millisecond presentation. These data show that faces are processed in a different way than a non-face object during the period from middle childhood through adolescence and adulthood, and this differential processing may involve the massive amount of exposure we have to faces.     

The role of pattern goodness in the reproduction of backward masked patterns.

Four experiments investigated the role of pattern goodness in backward masking using five- and four-dot patterns constructed by placing dots in the cells of a 3 x 3 matrix. In Experiment 1, subjects rated the goodness of these patterns and the results replicated previous work showing that good patterns had few alternatives. In Experiment 2, the dot patterns were the target stimuli in a backward masking task using a variety of masking stimuli. For all masking, good patterns were reproduced more accurately than poor patterns. In Experiment 3, the goodness of the masking stimulus was varied. The results indicated that good patterns were reproduced more accurately (replicating Experiment 2) and that good patterns were less effective as stimulus than were poor patterns. In Experiment 4, a long interstimulus interval which precluded masking was used to determine whether goodness affected encoding or memory. At these intervals, there were no differences among patterns, suggesting that the effect of pattern goodness was on rate of encoding. These results demonstrate the importance of configural properties in pattern perception.     

What we see: inattention and the capture of attention by meaning

Attention is necessary for the conscious perception of any object. Objects not attended to are not seen. What is it that captures attention when we are engaged in some attention-absorbing task? Earlier research has shown that there are only a very few stimuli which have this power and therefore are reliably detected under these conditions (for example, Mack & Rock, 1998; Moray, 1959). The two most reliable are the observer's own name and a happy face icon which seem to capture attention by virtue of their meaning. Three experiments are described which explore whether these stimuli are detected under conditions, heretofore unexamined, which either cause inattentional blindness or are associated with a perceptual failure associated with the limits of attention. The evidence obtained indicates that these stimuli have a unique capacity to capture and extend the limits of attention under conditions in which this has been deemed highly unlikely.     

Grabbing attention without knowing: Automatic capture of attention by subliminal spatial cues

The present study shows that an abrupt onset cue that is not consciously perceived can cause attentional facilitation followed by inhibition at the cued location. The observation of this classic biphasic effect of facilitation followed by inhibition of return (IOR) suggests that the subliminal cue captured attention in a purely exogenous way. Since IOR is not observed following endogenous shifts of spatial attention, but is observed following exogenous, stimulus-driven shifts of spatial attention, it is unlikely that top-down control settings or other non-attentional effects played a role. The current findings are interpreted in terms of a neurobiological model of visual awareness.     

Spatial effectiveness of the mask: Lateral inhibition in visual backward masking

Introducing a figure into a masking flash results in visual backward masking under conditions where a homogeneous masking flash does not suppress target detection. It is possible to analyze the spatial effects of such a masking figure in terms of lateral inhibition. It is hypothesized that incorporating a figure into the masking flash changes the inhibitory pattern the mask produces in the visual system. The interaction between the firing pattern produced by the mask and the residual inhibition from the preceding target presentation results in a phenomenal representation different from that produced by either the target or the mask alone.     

The capture of attention by entirely irrelevant pictures of calorie-dense foods

Inborn preference for palatable energy-dense food is thought to be an evolutionary adaptation. One way this preference manifests itself is through the control of visual attention. In the present study, we investigated how attentional capture is influenced by changes in naturally occurring goal-states, in this case desire for energy-dense foods (typically high fat and/or high sugar). We demonstrate that even when distractors are entirely irrelevant, participants were significantly more distracted by energy-dense foods compared with non-food objects and even low-energy foods. Additionally, we show the lability of these goal-states by having a separate set of participants consume a small amount of calorie-dense food prior to the task. The amount of distraction by the energy-dense food images in this case was significantly reduced and no different than distraction by images of low-energy foods and images of non-food objects. While naturally occurring goal-states can be difficult to ignore, they also are highly flexible.     

When motor attention improves selective attention: The dissociating role of saliency

There is evidence that preparing and maintaining a motor plan (“motor attention”) can bias visual selective attention. For example, a motor attended grasp biases visual attention to select appropriately graspable object features (Symes, Tucker, Ellis, Vainio, & Ottoboni, 2008). According to the biased competition model of selective attention, the relative weightings of stimulus-driven and goal-directed factors determine selection. The current study investigated how the goal-directed bias of motor attention might operate when the stimulus-driven salience of the target was varied. Using a change detection task, two almost identical photographed scenes of simplistic graspable objects were presented flickering back and forth. The target object changed visually, and this change was either high or low salience. Target salience determined whether or not the motor attended grasp significantly biased visual selective attention. Specifically, motor attention only had a reliable influence on target detection times when the visual salience of the target was low.     

Automaticity and the capture of attention by a peripheral display change

The proposal that peripheral visual changes (cues) tend to summon attention automatically was tested by studying the effect of peripheral cueing on simple detection latency. Delay between cue onset and target onset, the contingent relationship between cue location and target location, and instructions to subjects were manipulated. Results showed that a peripheral display change could capture attention even when the target was far more likely to appear at an uncued location. When subjects were explicitly informed that targets were likely to appear away from the cued location they were able to suppress this effect, but were unable completely to reverse it by rapidly orienting attention towards the uncued side. Hence the process appears to be automatic in the sense that it occurs unless there are explicit instructions to the contrary. With explicit instructions the processing operation can be suppressed, but not completely reversed. This work was supported by the U.K. Admiralty Research Establishment (Research Agreement No. 53482).     

The role of fear and expectancies in capture of covert attention by spiders

Fear-related stimuli are often prioritized during visual selection but it remains unclear whether capture by salient objects is more likely to occur when individuals fear those objects. In this study, participants with high and low fear of spiders searched for a circle while on some trials a completely irrelevant fear-related (spider) or neutral distractor (butterfly/leaf) was presented simultaneously in the display. Our results show that when you fear spiders and you are not sure whether a spider is going to be present, then any salient distractor (i.e., a butterfly) grabs your attention, suggesting that mere expectation of a spider triggered compulsory monitoring of all irrelevant stimuli. However, neutral stimuli did not grab attention when high spider fearful people knew that a spider could not be present during a block of trials, treating the neutral stimuli just as the low spider fearful people do. Our results show that people that fear spiders inspect potential spider-containing locations in a compulsory fashion even though directing attention to this location is completely irrelevant for the task. Reduction of capture can only be accomplished when people that fear spiders do not expect a spider to be present.     

The role of flicker and abrupt displacement in attention capture by motion onsets

Sunny and von Mühlenen (Psychonomic Bulletin & Review, 18, 1050–1056, 2011) showed that an onset of motion captured attention only when the motion was jerky (refreshed at 8 or 17 Hz), but not when it was smooth (33 or 100 Hz). However, it remained unclear why the onset of jerky motion captures attention. In the present study, we systematically tested the role of different aspects of jerky motion in capturing attention. Simple flicker without motion did not capture attention in the same way as jerky motion (Exp. 1). An abrupt displacement between 0.26° and 1.05° captured attention, irrespective of whether the stimulus subsequently continued to move smoothly (Exp. 2) or whether it remained stationary (Exps. 3 and 4). A displaced stimulus that was preceded briefly at the new location by a figure-8 placeholder did not capture attention (Exp. 5). These results are explained within a masking account, according to which abrupt onsets and abrupt displacements receive a processing advantage because they escape forward masking by the preceding figure-8 placeholders.     

The development of perceived structure and attention: evidence from divided and selective attention tasks

Three experiments provide converging evidence for the view that both perceived structure and attention change during the elementary school years. Kindergarteners, second graders, and adults performed three speeded tasks: divided attention to conjunctions of features, selective attention to orthogonal dimensions and selective attention to correlated dimensions. The tasks were performed with sizes and shapes that were either spatially integrated or spatially separated. In the divided attention task, conjunctions were identified as quickly as single features with integrated stimuli at all ages, but conjunctions were identified more slowly than single features with separated stimuli by all age group. In the orthogonal dimensions task, interference was observed with integrated stimuli across ages, but the interference in adult performance was asymmetric. With separated stimuli, interference was gradually eliminated with increasing age. In correlated dimensions tasks, younger children showed a redundancy gain with integrated stimuli, but no gain was observed in the performances of the older subjects. With separated stimuli there was no redundancy gain at any age. These results were interpreted to mean that integrated stimuli are initially perceived as wholes by all subjects, but that features become more accessible with increasing age. Even so, attention remains constrained by stimulus structure. In contrast, separated stimuli are initially perceived as features at all ages, and the improvement in performance with increasing age is attributable to the increasing command of attentional resources that accompanies development. Our discussion of these findings focuses on three issues: multiple trends in perceptual development, the characteristics of an adequate theory of perceptual representation and processing, and a comparison of the separability hypothesis and other developmental accounts of perceptual development.     

Attentional capture and hold: the oculomotor correlates of the change detection advantage for faces

The present study investigated the influence of semantic information on overt attention. Semantic influence on attentional capture and hold mechanisms was explored by measuring oculomotor correlates of the reaction time (RT) and accuracy advantage for faces in the change detection task. We also examined whether the face advantage was due to mandatory processing of faces or an idiosyncratic strategy by participants, by manipulating preknowledge of the object category in which to expect a change. An RT and accuracy advantage was found for detecting changes in faces compared to other objects of less social and biological significance, in the form of greater attentional capture and hold. The faster attentional capture by faces appeared to overcompensate for the longer hold, to produce faster and more accurate manual responses. Preknowledge did not eliminate the face advantage, suggesting that faces receive mandatory processing when competing for attention with stimuli of less sociobiological salience.     

The selective attention of learning-disabled children: Three studies

Three studies were performed to assess the selective attention of learning-disabled (LD) children. In the first study, 10 LD and 16 non-LD children were given the Speeded Classification task. LD children sorted cards more slowly than non-LD children, and children in both groups had trouble ignoring irrelevant information. Non-LD children became more accurate across trials, while LD children did not. In the second study, one group of 13 LD children was taught to accompany their Speeded Classification sorting verbally in an attempt to improve their performance; the other group of LD children (n=12) received no such instruction. The experimental group, however, showed poorer performance across trials compared with the control group. In the third study, the children from Experiments 1 and 2 were given the Central-Incidental Learning task. Older children learned more central memory items than younger children and, LD children learned more incidentally than non-LD children.The authors would like to thank James Merola, Lisa Hart, Donna Woods, and Leonne Paquette for their assistance in this project, and the headmaster, director, teachers, and staff who were so helpful. Parts of this paper were presented at the 1982 meeting of the American Psychological Association.     

Temporal processing of emotional stimuli: the capture and release of attention by angry faces

Neuroimaging data suggest that emotional information, especially threatening faces, automatically captures attention and receives rapid processing. While this is consistent with the majority of behavioral data, behavioral studies of the attentional blink (AB) additionally reveal that aversive emotional first target (T1) stimuli are associated with prolonged attentional engagement or "dwell" time. One explanation for this difference is that few AB studies have utilized manipulations of facial emotion as the T1. To address this, schematic faces varying in expression (neutral, angry, happy) served as the T1 in the current research. Results revealed that the blink associated with an angry T1 face was, primarily, of greater magnitude than that associated with either a neutral or happy T1 face, and also that initial recovery from this processing bias was faster following angry, compared with happy, T1 faces. The current data therefore provide important information regarding the time-course of attentional capture by angry faces: Angry faces are associated with both the rapid capture and rapid release of attention.     

Responding to the direction of the eyes: In search of the masked gaze-cueing effect

Recent studies have demonstrated that masked gaze cues can produce a cueing effect. Those studies, however, all utilized a localization task and, hence, are ambiguous with respect to whether the previously observed masked gaze-cueing effect reflects the orienting of attention or the preparation of a motor response. The aim of the present study was to investigate this issue by determining whether masked gaze cues can modulate responses in detection and discrimination tasks, both of which isolate spatial attention from response priming. First, we found a gaze-cueing effect for unmasked cues in detection, discrimination, and localization tasks, which suggests that the gaze-cueing effect for visible cues is not task dependent. Second, and in contrast, we found a gaze-cueing effect for masked cues in a localization task, but not in detection or discrimination tasks, which suggests that the gaze-cueing effect for masked cues is task dependent. Therefore, the present study shows that the masked gaze-cueing effect is attributed to response priming, as opposed to the orienting of spatial attention.     

Development of selective attention in young infants: Enhancement and attenuation of startle reflex by attention

This study examined the effect of level of attention engagement on the modification of the blink reflex in young infants. Infants at 8, 14, 20, or 26 weeks of age were presented with interesting visual or auditory stimuli. At delays defined by changes in heart rate known to be associated with sustained attention or attention disengagement, blink reflexes were elicited by visual or auditory blink reflex stimuli. Blink amplitude varied according to the level of attention, and the match between the foreground and blink reflex stimulus. If the infant was attending to the foreground stimulus, a blink reflex stimulus in the same modality resulted in enhanced blink reflex magnitude. A blink reflex stimulus in the other modality resulted in an attenuated blink reflex magnitude. If attention was not engaged with the foreground stimulus, this modulation of the blink reflex did not occur. This ‘selective modality effect’ showed an increasing tendency to occur between 8 and 26 weeks of age. These results show that selective attention to modalities increases over this age range.