Attention to upside-down faces: An exception to the inversion effect

Social perception of animacy: Preferential attentional orienting to animals links with autistic traits

Animate cues enjoy priority in attentional processes as they carry survival-relevant information and herald social interaction. Whether and in what way such an attention effect is associated with more general aspects of social cognition remains largely unexplored. Here we investigated whether the attentional preference for animals varies with observers' autistic traits - an indicator of autism-like characteristics in general populations related to one's social cognitive abilities. Using the dot-probe paradigm, we found that animal cues can rapidly and persistently recruit preferential attention over inanimate ones in observers with relatively low, but not high, autistic traits, as measured by Autism-Spectrum Quotient (AQ). Moreover, individual AQ scores were negatively correlated with the attentional bias toward animals, especially at the early orienting stage. These results were not simply due to low-level visual factors, as inverted or phase-scrambled pictures did not yield a similar pattern. Our findings demonstrate an automatic and enduring attentional bias beneficial to both rapid detection and continuous monitoring of animals and reveal its link with autistic traits, highlighting the critical role of animacy perception in the architecture of social cognition.

The generality of the attentional boost effect for famous, unfamiliar, and inverted faces

Familiarity and face inversion not only affect face recognition and memory but also influence attention. Face processing is less attention-demanding for familiar than for unfamiliar faces and for upright than for inverted faces. The automaticity raises the question of how face processing interacts with an increase in attention. Using a dual-task paradigm, we tested the interaction between attention and face familiarity and orientation. Participants encoded a series of faces to memory while simultaneously monitoring a stream of colored squares, pressing the space bar for target-colored squares and making no response to distractor-colored squares. Replicating previous findings of the attentional boost effect (ABE), we found that faces encoded with target squares were better remembered than faces encoded with distractor squares. If the automatic nature of familiar (or upright) face processing makes attention unnecessary, then the attentional boost should be attenuated for familiar relative to unfamiliar faces and for upright relative to inverted faces. Data from three experiments showed, however, that the ABE was the same for all types of faces. These results suggest that target detection did not simply elevate attention in an early encoding phase. Rather, selecting targets and rejecting distractors in the color task may have led to yoked temporal selection of target-concurrent faces for entry into memory.

Infrequent faces bias social attention differently in manual and oculomotor measures

Although attention is thought to be spontaneously biased by social cues like faces and eyes, recent data have demonstrated that when extraneous content, context, and task factors are controlled, attentional biasing is abolished in manual responses while still occurring sparingly in oculomotor measures. Here, we investigated how social attentional biasing was affected by face novelty by measuring responses to frequently presented (i.e., those with lower novelty) and infrequently presented (i.e., those with higher novelty) face identities. Using a dot-probe task, participants viewed either the same face and house identity that was frequently presented on half of the trials or sixteen different face and house identities that were infrequently presented on the other half of the trials. A response target occurred with equal probability at the previous location of the eyes or mouth of the face or the top or bottom of the house. Experiment 1 measured manual responses to the target while participants maintained central fixation. Experiment 2 additionally measured participants' natural oculomotor behaviour when their eye movements were not restricted. Across both experiments, no evidence of social attentional biasing was found in manual data. However, in Experiment 2, there was a reliable oculomotor bias towards the eyes of infrequently presented upright faces. Together, these findings suggest that face novelty does not facilitate manual measures of social attention, but it appears to promote spontaneous oculomotor biasing towards the eyes of infrequently presented novel faces.

Visual perspective-taking in complex natural scenes

Studies of visual perspective-taking have shown that adults can rapidly and accurately compute their own and other peoples’ viewpoints, but they experience difficulties when the two perspectives are inconsistent. We tested whether these egocentric (i.e., interference from one’s own perspective) and altercentric biases (i.e., interference from another person’s perspective) persist in ecologically valid complex environments. Participants (N = 150) completed a dot-probe visual perspective-taking task, in which they verified the number of discs in natural scenes containing real people, first only according to their own perspective and then judging both their own and another person’s perspective. Results showed that the other person’s perspective did not disrupt self perspective-taking judgements when the other perspective was not explicitly prompted. In contrast, egocentric and altercentric biases were found when participants were prompted to switch between self and other perspectives. These findings suggest that altercentric visual perspective-taking can be activated spontaneously in complex real-world contexts, but is subject to both top-down and bottom-up influences, including explicit prompts or salient visual stimuli.

Isolated face features are sufficient to elicit ultra-rapid and involuntary orienting responses toward faces

Previous studies have shown that face stimuli influence the programming of eye movements by eliciting involuntary and extremely fast saccades toward them. The present study examined whether holistic processing of faces mediates these effects. We used a saccadic choice task in which participants were presented simultaneously with two images and had to perform a saccade toward the one containing a target stimulus (e.g., a face). Across three experiments, stimuli were altered via upside-down inversion (Experiment 1) or scrambling of thumbnails within the images (Experiments 2 and 3) in order to disrupt holistic processing. We found that disruption of holistic processing only had a limited impact on the latency of saccades toward face targets, which remained extremely short (minimum saccadic reaction times of only ∼120–130 ms), and did not affect the proportion of error saccades toward face distractors that captured attention more than other distractor categories. It, however, resulted in increasing error rate of saccades toward face targets. These results suggest that the processing of isolated face features is sufficient to elicit extremely fast and involuntary saccadic responses toward them. Holistic representations of faces may, however, be used as a search template to accurately detect faces.

Unravelling how low dominance in faces biases non-spatial attention

According to the Dual Dodel of Social Hierarchy, one pathway for attaining social status is through dominance (coercion and intimidation). High dominance stimuli are known to more readily attract eye gaze and social attention. However, when there is a competition for non-spatial attentional resources, low dominance stimuli show an advantage. This low dominance bias was hypothesised to occur due to either counter-stereotypicality or attention competition. Here, these two hypotheses were examined across two experiments using modified versions of the attentional blink paradigm, used to measure non-spatial attention, and manipulations of facial dominance in both males and females. The results support the attention competition theory, suggesting that low dominance stimuli have a consistently strong ability to compete for attentional resources. Unexpectedly, high dominance stimuli fluctuate between having a strong and weak ability to compete for the same resources. The results challenge the current understanding of how humans interact with status.

Contextually-Based Social Attention Diverges across Covert and Overt Measures

Humans spontaneously attend to social cues like faces and eyes. However, recent data show that this behavior is significantly weakened when visual content, such as luminance and configuration of internal features, as well as visual context, such as background and facial expression, are controlled. Here, we investigated attentional biasing elicited in response to information presented within appropriate background contexts. Using a dot-probe task, participants were presented with a face-house cue pair, with a person sitting in a room and a house positioned within a picture hanging on a wall. A response target occurred at the previous location of the eyes, mouth, top of the house, or bottom of the house. Experiment 1 measured covert attention by assessing manual responses while participants maintained central fixation. Experiment 2 measured overt attention by assessing eye movements using an eye tracker. The data from both experiments indicated no evidence of spontaneous attentional biasing towards faces or facial features in manual responses; however, an infrequent, though reliable, overt bias towards the eyes of faces emerged. Together, these findings suggest that contextually-based social information does not determine spontaneous social attentional biasing in manual measures, although it may act to facilitate oculomotor behavior.

The eyes do not have it after all? Attention is not automatically biased towards faces and eyes

It is commonly accepted that attention is spontaneously biased towards faces and eyes. However, the role of stimulus features and task settings in this finding has not yet been systematically investigated. Here, we tested if faces and facial features bias attention spontaneously when stimulus factors, task properties, response conditions, and eye movements are controlled. In three experiments, participants viewed face, house, and control scrambled face-house images in an upright and inverted orientation. The task was to discriminate a target that appeared with equal probability at the previous location of the face, house, or the control image. In all experiments, our data indicated no spontaneous biasing of attention for targets occurring at the previous location of the face. Experiment 3, which measured oculomotor biasing, suggested a reliable but infrequent saccadic bias towards the eye region of upright faces. Importantly, these results did not reflect our specific laboratory settings, as in Experiment 4, we present a full replication of a classic finding in the literature demonstrating reliable social attention bias. Together, these data suggest that attentional biasing for social information is task and context mediated, and less robust than originally thought.

Efficient search for a face by chimpanzees (Pan troglodytes)

The face is quite an important stimulus category for human and nonhuman primates in their social lives. Recent advances in comparative-cognitive research clearly indicate that chimpanzees and humans process faces in a special manner; that is, using holistic or configural processing. Both species exhibit the face-inversion effect in which the inverted presentation of a face deteriorates their perception and recognition. Furthermore, recent studies have shown that humans detect human faces among non-facial objects rapidly. We report that chimpanzees detected chimpanzee faces among non-facial objects quite efficiently. This efficient search was not limited to own-species faces. They also found human adult and baby faces-but not monkey faces-efficiently. Additional testing showed that a front-view face was more readily detected than a profile, suggesting the important role of eye-to-eye contact. Chimpanzees also detected a photograph of a banana as efficiently as a face, but a further examination clearly indicated that the banana was detected mainly due to a low-level feature (i.e., color). Efficient face detection was hampered by an inverted presentation, suggesting that configural processing of faces is a critical element of efficient face detection in both species. This conclusion was supported by a simple simulation experiment using the saliency model.

Oculomotor guidance and capture by irrelevant faces

Even though it is generally agreed that face stimuli constitute a special class of stimuli, which are treated preferentially by our visual system, it remains unclear whether faces can capture attention in a stimulus-driven manner. Moreover, there is a long-standing debate regarding the mechanism underlying the preferential bias of selecting faces. Some claim that faces constitute a set of special low-level features to which our visual system is tuned; others claim that the visual system is capable of extracting the meaning of faces very rapidly, driving attentional selection. Those debates continue because many studies contain methodological peculiarities and manipulations that prevent a definitive conclusion. Here, we present a new visual search task in which observers had to make a saccade to a uniquely colored circle while completely irrelevant objects were also present in the visual field. The results indicate that faces capture and guide the eyes more than other animated objects and that our visual system is not only tuned to the low-level features that make up a face but also to its meaning.

Temporal profile of amygdala γ oscillations in response to faces

Neuroimaging studies have reported greater activation of the human amygdala in response to faces than to nonfacial stimuli, yet little is known about the temporal profile of this activation. We investigated this issue by recording the intracranial field potentials of the amygdala in participants undergoing preneurosurgical assessment (n = 6). Participants observed faces, mosaics, and houses in upright and inverted orientations using a dummy target detection task. Time-frequency statistical parametric mapping analyses revealed that the amygdala showed greater gamma-band activity in response to faces than to mosaics at 200-300 msec, with a peak at 255 msec. Gamma-band activation with a similar temporal profile was also found in response to faces versus houses. Activation patterns did not differ between upright and inverted presentations of stimuli. These results suggest that the human amygdala is involved in the early stages of face processing, including the modulation of subjective perception of faces.

The role of gamma-band activity in the representation of faces: reduced activity in the fusiform face area in congenital prosopagnosia

BACKGROUND

Congenital prosopagnosia (CP) describes an impairment in face processing that is presumably present from birth. The neuronal correlates of this dysfunction are still under debate. In the current paper, we investigate high-frequent oscillatory activity in response to faces in persons with CP. Such neuronal activity is thought to reflect higher-level representations for faces.

METHODOLOGY

Source localization of induced Gamma-Band Responses (iGBR) measured by magnetoencephalography (MEG) was used to establish the origin of oscillatory activity in response to famous and unknown faces which were presented in upright and inverted orientation. Persons suffering from congenital prosopagnosia (CP) were compared to matched controls.

PRINCIPAL FINDINGS

Corroborating earlier research, both groups revealed amplified iGBR in response to upright compared to inverted faces predominately in a time interval between 170 and 330 ms and in a frequency range from 50-100 Hz. Oscillatory activity upon known faces was smaller in comparison to unknown faces, suggesting a "sharpening" effect reflecting more efficient processing for familiar stimuli. These effects were seen in a wide cortical network encompassing temporal and parietal areas involved in the disambiguation of homogenous stimuli such as faces, and in the retrieval of semantic information. Importantly, participants suffering from CP displayed a strongly reduced iGBR in the left fusiform area compared to control participants.

CONCLUSIONS

In sum, these data stress the crucial role of oscillatory activity for face representation and demonstrate the involvement of a distributed occipito-temporo-parietal network in generating iGBR. This study also provides the first evidence that persons suffering from an agnosia actually display reduced gamma band activity. Finally, the results argue strongly against the view that oscillatory activity is a mere epiphenomenon brought fourth by rapid eye-movements (micro saccades).

Faces capture the visuospatial attention of chimpanzees (Pan troglodytes): evidence from a cueing experiment

Background

Faces, as socially relevant stimuli, readily capture human visuospatial attention. Although faces also play important roles in the social lives of chimpanzees, the closest living species to humans, the way in which faces are attentionally processed remains unclear from a comparative-cognitive perspective. In the present study, three young chimpanzees (Pan troglodytes) were tested with a simple manual response task in which various kinds of photographs, including faces as non-informative cues, were followed by a target.

Results

When the target appeared at the location that had been occupied by the face immediately before target onset, response times were significantly faster than when the target appeared at the opposite location that had been by the other object. Such an advantage was not observed when a photograph of a banana was paired with the other object. Furthermore, this attentional capture was also observed when upright human faces were presented, indicating that this effect is not limited to own-species faces. On the contrary, when the participants were tested with inverted chimpanzee faces, this effect was rather weakened, suggesting the specificity to upright faces.

Conclusion

Chimpanzee's visuospatial attention was easily captured by the face stimuli. This effect was face specific and stronger for upright faces than inverted. These results are consistent with those from typically developing humans.