More efficient rejection of happy than of angry face distractors in visual search

In the present study, we examined whether the detection advantage for negative-face targets in crowds of positive-face distractors over positive-face targets in crowds of negative faces can be explained by differentially efficient distractor rejection. Search Condition A demonstrated more efficient distractor rejection with negative-face targets in positive-face crowds than vice versa. Search Condition B showed that target identity alone is not sufficient to account for this effect, because there was no difference in processing efficiency for positive- and negative-face targets within neutral crowds. Search Condition C showed differentially efficient processing with neutral-face targets among positive- or negative-face distractors. These results were obtained with both a within-participants (Experiment 1) and a between-participants (Experiment 2) design. The pattern of results is consistent with the assumption that efficient rejection of positive (more homogenous) distractors is an important determinant of performance in search among (face) distractors.     

The effect of face inversion on the detection of emotional faces in visual search

Past literature has indicated that face inversion either attenuates emotion detection advantages in visual search, implying that detection of emotional expressions requires holistic face processing, or has no effect, implying that expression detection is feature based. Across six experiments that utilised different task designs, ranging from simple (single poser, single set size) to complex (multiple posers, multiple set sizes), and stimuli drawn from different databases, significant emotion detection advantages were found for both upright and inverted faces. Consistent with past research, the nature of the expression detection advantage, anger superiority (Experiments 1, 2 and 6) or happiness superiority (Experiments 3, 4 and 5), differed across stimulus sets. However both patterns were evident for upright and inverted faces. These results indicate that face inversion does not interfere with visual search for emotional expressions, and suggest that expression detection in visual search may rely on feature-based mechanisms.     

Angry faces are more resistant to forgetting than are happy faces: directed forgetting effects on the identity of emotional faces

Using the item-method directed forgetting paradigm (i.e. intentionally forgetting specified information), we examined directed forgetting of facial identity as a function of facial expression and the sex of the expresser and perceiver. Participants were presented with happy and angry male and female faces cued for either forgetting or remembering, and were then asked to recognise previously studied faces from among a series of neutral faces. For each recognised test face, participants also recalled the face’s previously displayed emotional expression. We found that angry faces were more resistant to forgetting than were happy faces. Furthermore, angry expressions on male faces and happy expressions on female faces were recognised and recalled better than vice versa. Signal detection analyses revealed that male faces gave rise to a greater sensitivity than female faces did, and male participants, but not female participants, showed greater sensitivity to male faces than to female faces. Several theoretical implications are discussed.     

Facing threat: infants' and adults' visual scanning of faces with neutral, happy, sad, angry, and fearful emotional expressions

Human faces are among the most important visual stimuli that we encounter at all ages. This importance partly stems from the face as a conveyer of information on the emotional state of other individuals. Previous research has demonstrated specific scanning patterns in response to threat-related compared to non-threat-related emotional expressions. This study investigated how visual scanning patterns toward faces which display different emotional expressions develop during infancy. The visual scanning patterns of 4-month-old and 7-month-old infants and adults when looking at threat-related (i.e., angry and fearful) versus non-threat-related (i.e., happy, sad, and neutral) emotional faces were examined. We found that infants as well as adults displayed an avoidant looking pattern in response to threat-related emotional expressions with reduced dwell times and relatively less fixations to the inner features of the face. In addition, adults showed a pattern of eye contact avoidance when looking at threat-related emotional expressions that was not yet present in infants. Thus, whereas a general avoidant reaction to threat-related facial expressions appears to be present from very early in life, the avoidance of eye contact might be a learned response toward others' anger and fear that emerges later during development.     

Components of the location probability effect in visual search tasks

In visual search tasks, targets are detected more rapidly when they appear in locations that commonly contain a target than when they appear in locations that rarely contain a target. Five experiments were conducted to investigate two specific properties of this location probability effect: its dependence on spatial location versus relative position and its dependence on or independence of target identity. In Experiment 1 spatial location of a stimulus row was varied to determine whether high location probability facilitates target detection in a particular location in visual space or a particular relative position within the row. Both were facilitated to approximately the same extent. In Experiment 2 an inducing target occurred with high probability in one of four display locations, and a test target occurred with equal probability in all four locations. Both targets were found more quickly in the high-probability location than in the other locations, but the advantage associated with targets in the high-probability location was larger for the inducing target than for the test target. In Experiments 3-5 the correspondence between the components observed in Experiments 1 and 2 was examined. The overall pattern of results was compatible with a model in which the location probability effect is produced partly by an attentional spotlight, which facilitates processing of any stimulus appearing in a particular location in visual space, and partly by a network of position-specific letter detectors, which facilitates detection of a particular letter in a particular relative position within a display. Models with flexible scanning strategies were also considered.     

Affect and face perception: odors modulate the recognition advantage of happy faces

Previous choice reaction time studies have provided consistent evidence for faster recognition of positive (e.g., happy) than negative (e.g., disgusted) facial expressions. A predominance of positive emotions in normal contexts may partly explain this effect. The present study used pleasant and unpleasant odors to test whether emotional context affects the happy face advantage. Results from 2 experiments indicated that happiness was recognized faster than disgust in a pleasant context, but this advantage disappeared in an unpleasant context because of the slow recognition of happy faces. Odors may modulate the functioning of those emotion-related brain structures that participate in the formation of the perceptual representations of the facial expressions and in the generation of the conceptual knowledge associated with the signaled emotion.     

Why faces are and are not special: an effect of expertise

Recognition memory for faces is hampered much more by inverted presentation than is memory for any other material so far examined. The present study demonstrates that faces are not unique with regard to this vulnerability to inversion. The experiments also attempt to isolate the source of the inversion effect. In one experiment, use of stimuli (landscapes) in which spatial relations among elements are potentially important distinguishing features is shown not to guarantee a large inversion effect. Two additional experiments show that for dog experts sufficiently knowledgeable to individuate dogs of the same breed, memory for photographs of dogs of that breed is as disrupted by inversion as is face recognition. A final experiment indicates that the effect of orientation on memory for faces does not depend on inability to identify single features of these stimuli upside down. These experiments are consistent with the view that experts represent items in memory in terms of distinguishing features of a different kind than do novices. Speculations as to the type of feature used and neuropsychological and developmental implications of this accomplishment are offered.     

Emotional facial expressions and the attentional blink: Attenuated blink for angry and happy faces irrespective of social anxiety

Although facial information is distributed over spatial as well as temporal domains, thus far research on selective attention to disapproving faces has concentrated predominantly on the spatial domain. This study examined the temporal characteristics of visual attention towards facial expressions by presenting a Rapid Serial Visual Presentation (RSVP) paradigm to high (n=33) and low (n=34) socially anxious women. Neutral letter stimuli (p, q, d, b) were presented as the first target (T1), and emotional faces (neutral, happy, angry) as the second target (T2). Irrespective of social anxiety, the attentional blink was attenuated for emotional faces. Emotional faces as T2 did not influence identification accuracy of a preceding (neutral) target. The relatively low threshold for the (explicit) identification of emotional expressions is consistent with the view that emotional facial expressions are processed relatively efficiently.     

Race as a visual feature: using visual search and perceptual discrimination tasks to understand face categories and the cross-race recognition deficit

One of the most familiar empirical phenomena associated with face recognition is the cross-race (CR) recognition deficit whereby people have difficulty recognizing members of a race different from their own. Most researchers assume that the CR deficit is caused by failure to generalize perceptual encoding expertise from same-race (SR) faces to CR faces. However, this explanation ignores critical differences in the social cognitions and feature coding priorities associated with SR and CR faces. On the basis of data from visual search and perceptual discrimination tasks, it appears that the deficit occurs because people emphasize visual information specifying race at the expense of individuating information when recognizing CR faces. In particular, it is possible to observe a paradoxical improvement in both detection and perceptual discrimination accuracy for CR faces that is limited to those who recognize them poorly. These findings support a new explanation for the CR recognition deficit based on feature coding differences between CR and SR faces, and appear incompatible with similarity-based models of face categories.     

First fixations in face processing: The more diagnostic they are the smaller the face-inversion effect

Hills, Ross, and Lewis (2011) introduced the concept that the face-inversion effect may, in part, be carried by the first feature attended to, since the first feature fixated upon is different for upright and inverted faces. An eye-tracking study that directly assesses this hypothesis by using fixation crosses to guide attention to the eye or mouth region of the to-be-presented upright and inverted faces was devised. Recognition was better when the fixation cross appeared at the eye region than at the mouth region. The face-inversion effect was smaller when the eyes were cued than when the mouth was cued or when there was no cueing. The eye-tracking measures confirmed that the fixation crosses attracted the first fixation but did not affect other measures of eye-movements. Furthermore, the location of the first fixation predicted recognition accuracy: when the first fixation was to the eyes, recognition accuracy was higher than when the first fixation was to the mouth, irrespective of facial orientation. The results suggest that the first facial feature attended to is more predictive of recognition accuracy than the face orientation in which they are presented.     

The face in the crowd effect: Threat-detection advantage with perceptually intermediate distractors

The ability to quickly perceive threatening facial expressions allows one to detect emotional states and respond appropriately. The anger superiority hypothesis predicts that angry faces capture attention faster than happy faces. Previous studies have used photographic (Hansen & Hansen, 1988) and schematic face images (e.g., Eastwood, Smilek, & Merikle, 2001; Ohman, Lunqvist, & Esteves, 2001) in studying the anger superiority effect, but specific confounds due to the construction of stimuli have led to conflicting findings. In the current study, participants performed a visual search for either angry or happy target faces among crowds of novel, perceptually intermediate morph distractors. A threat-detection advantage was evident where participants showed faster reaction times and greater accuracy in detecting angry over happy faces. Search slopes, however, did not significantly differ. Results suggest a threat-detection advantage mediated by serial rather than preattentive processing.     

Finding the face in the crowd: an anger superiority effect

Facial gestures have been given an increasingly critical role in models of emotion. The biological significance of interindividual transmission of emotional signals is a pivotal assumption for placing the face in a central position in these models. This assumption invited a logical corollary, examined in this article: Face-processing should be highly efficient. Three experiments documented an asymmetry in the processing of emotionally discrepant faces embedded in crowds. The results suggested that threatening faces pop out of crowds, perhaps as a result of a preattentive, parallel search for signals of direct threat.     

Not just another face in the crowd: Detecting emotional schematic faces during continuous flash suppression

To test whether threatening visual information receives prioritized processing, many studies have examined visual search for emotional schematic faces. Still, it has remained unclear whether negative or positive schematic faces are processed more efficiently. We used continuous flash suppression, a variant of binocular rivalry, to render single emotional schematic faces invisible and measured whether negative or positive faces have an advantage in accessing awareness. Across three experiments, positive faces were detected more quickly than negative faces. A fourth experiment indicated that this positive face advantage was unrelated to the valence of the face stimuli but due to the relative orientation of the mouth curvature and the face contour. These findings demonstrate the impact of configural stimulus properties on perceptual suppression during binocular rivalry and point to a perceptual confound present in emotional schematic faces that might account for some ambiguous results obtained with schematic face stimuli in previous studies. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Eye-tracking the own-gender bias in face recognition: Other-gender faces are viewed differently to own-gender faces

Research on the own-gender bias in face recognition has indicated an asymmetrical effect: an effect found only in women. We investigated the own-gender bias, using an eye-tracker to examine whether the own-gender bias is associated with differential processing strategies. We found an own-gender bias in our female participants. Our eye-tracking analysis indicated different scanning behaviours when processing own- and other-gender faces, with longer and more fixations to the eyes when viewing own-gender faces. Our results favour the socio-cognitive model, whilst acknowledging the role of perceptual expertise in the own-gender bias.     

When inverted faces are recognized: The role of configural information in face recognition

The identification of upright faces seems to involve a special sensitivity to "configural" information, the processing of which is less effective when the face is inverted. However the precise meaning of "configural" remains unclear. Five experiments are presented, which showed that the disruption of the processing of relational, rather than holistic, information largely determines the occurrence as well as the size of the face-inversion effect. In Experiment 1, faces could be identified either by unique combinations of local information (e.g. a specific eye colour plus hair colour) or by unique relational information (e.g. nose-mouth distance). The former showed no inversion effect, whereas the latter did. A combination of local and relational information (Experiment 2) again produced an inversion effect, although this effect was smaller than that found when only relational information was used. The results were replicated in Experiment 3 when differences in the brightness of local features were used instead of specific colour combinations. Experiment 4 used different retrieval conditions to distinguish relational from holistic processing, and demonstrated again that spatial relations between single features appeared to provide crucial information for face recognition. In Experiment 5, the importance of relational information was confirmed using faces that also varied in the shapes of local features.     

Repetition priming in visual search: Episodic retrieval,not feature priming

Previous research has shown that when the targets of successive visual searches have features in common, response times are shorter. However, the nature of the representation underlying this priming and how priming is affected by the task remain uncertain. In four experiments, subjects searched for an odd-sized target and reported its orientation. The color of the items was irrelevant to the task. When target size was repeated from the previous trial, repetition of target color speeded the response. However, when target size was different from that in the previous trial, repetition of target color slowed responses, rather than speeding them. Our results suggest that these priming phenomena reflect the same automatic mechanism as the priming of pop-out reported by Maljkovic and Nakayama (1994). However, the crossover interaction between repetition of one feature and another rules out Maljkovic and Nakayama's (1994) theory of independent potentiation of distinct feature representations. Instead, we suggest that the priming pattern results from contact with an episodic memory representation of the previous trial.     

Finding a face in the crowd: testing the anger superiority effect in Asperger Syndrome

Social threat captures attention and is processed rapidly and efficiently, with many lines of research showing involvement of the amygdala. Visual search paradigms looking at social threat have shown angry faces 'pop-out' in a crowd, compared to happy faces. Autism and Asperger Syndrome (AS) are neurodevelopmental conditions characterised by social deficits, abnormal face processing, and amygdala dysfunction. We tested adults with high-functioning autism (HFA) and AS using a facial visual search paradigm with schematic neutral and emotional faces. We found, contrary to predictions, that people with HFA/AS performed similarly to controls in many conditions. However, the effect was reduced in the HFA/AS group when using widely varying crowd sizes and when faces were inverted, suggesting a difference in face-processing style may be evident even with simple schematic faces. We conclude there are intact threat detection mechanisms in AS, under simple and predictable conditions, but that like other face-perception tasks, the visual search of threat faces task reveals atypical face-processing in HFA/AS.     

Training older adults to search more effectively: scanning strategy and visual search in dynamic displays

The authors examined the ability of older adults to modify their search strategies to detect changes in dynamic displays. Older adults who made few eye movements during search (i.e., covert searchers) were faster and more accurate compared with individuals who made many eye movements (i.e., overt searchers). When overt searchers were instructed to adopt a covert search strategy, target detection performance increased to the level of natural covert searchers. Similarly, covert searchers instructed to search overtly exhibited a decrease in target detection performance. These data suggest that with instructions and minimal practice, older adults can ameliorate the cost of a poor search strategy.     

The transference of visual search between two unrelated tasks: Measuring the temporal characteristics of carry-over

Investigations into the persistence of top-down control settings do not accurately reflect the nature of dynamic tasks. They typically involve extended practice with an initial task, and this initial task usually shares similar stimuli with a second task. Recent work shows that visual attention and search can be affected by limited exposure to a preceding, unrelated task, and the current study explored the temporal characteristics of this “carry-over” effect. Thirty-four participants completed one, four, or eight simple letter searches and then searched a natural scene. The spatial layout of letters influenced spread of search in the pictures, and this was further impacted by the time spent in the initial task, yet the carry-over effect diminished quickly. The results have implications for theories of top-down control and models that attempt to predict search in natural scenes. They are also relevant to real-world tasks in which performance is closely related to visual attention and search.