Markus Bindemann

Faces retain attention

In the present study, we investigated whether faces have an advantage in retaining attention over other stimulus categories. In three experiments, subjects were asked to focus on a central go/no-go signal before classifying a concurrently presented peripheral line target. In Experiment 1, the go/no-go signal could be superimposed on photographs of upright famous faces, matching inverted faces, or meaningful objects. Experiments 2 and 3 tested upright and inverted unfamiliar faces, printed names, and another class of meaningful objects in an identical design. A fourth experiment provided a replication of Experiment 1, but with a 1,000-msec stimulus onset asynchrony between the onset of the central face/nonface stimuli and the peripheral targets. In all the experiments, the presence of an upright face significantly delayed target response times, in comparison with each of the other stimulus categories. These results suggest a general attentional bias, so that it is particularly difficult to disengage processing resources from faces.

Viewpoint and center of gravity affect eye movements to human faces

In everyday life, human faces are encountered in many different views. Despite this fact, most psychological research has focused on the perception of frontal faces. To address this shortcoming, the current study investigated how different face views are processed, by measuring eye movements to frontal, mid-profile and profile faces during a gender categorization (Experiment 1) and a free-viewing task (Experiment 2). In both experiments observers initially fixated the geometric center of a face, independent of face view. This center-of-gravity effect induced a qualitative shift in the features that were sampled across different face views in the time period immediately after stimulus onset. Subsequent eye fixations focused increasingly on specific facial features. At this stage, the eye regions were targeted predominantly in all face views, and to a lesser extent also the nose and the mouth. These findings show that initial saccades to faces are driven by general stimulus properties, before eye movements are redirected to the specific facial features in which observers take an interest. These findings are illustrated in detail by plotting the distribution of fixations, first fixations, and percentage fixations across time.

How do eye gaze and facial expression interact

Previous research has demonstrated an interaction between eye gaze and selected facial emotional expressions, whereby the perception of anger and happiness is impaired when the eyes are horizontally averted within a face, but the perception of fear and sadness is enhanced under the same conditions. The current study reexamined these claims over six experiments. In the first three experiments, the categorization of happy and sad expressions (Experiments 1 and 2) and angry and fearful expressions (Experiment 3) was impaired when eye gaze was averted, in comparison to direct gaze conditions. Experiment 4 replicated these findings in a rating task, which combined all four expressions within the same design. Experiments 5 and 6 then showed that previous findings, that the perception of selected expressions is enhanced under averted gaze, are stimulus and task-bound. The results are discussed in relation to research on facial expression processing and visual attention.

Brain potential correlates of face recognition: Geometric distortions and the N250r brain response to stimulus repetitions

The N250r is an event-related potential that has been related to activation of image-independent representations of familiar faces during recognition. However, N250r also shows a degree of image specificity, with reduced activation across repetitions of different images of the same face compared to repetitions across the same image, suggesting a component that codes the visual overlap between two face images. This study investigated whether N250r is equally attenuated when horizontally or vertically stretched faces prime an unstretched image of the same face. The results confirm that N250r is larger across repetitions of the same face image than across different images of the same face. Despite this, N250r was equivalent for priming by the same face image and priming from stretched onto unstretched faces. This finding demonstrates that N250r does not simply reflect the superficial visual overlap between two face images and supports the notion that it is related to person recognition.

The control of attention to faces

Humans attend to faces. This study examines the extent to which attention biases to faces are under top-down control. In a visual cueing paradigm, observers responded faster to a target probe appearing in the location of a face cue than of a competing object cue (Experiments 1a and 2a). This effect could be reversed when faces were negatively predictive of the likely target location, making it beneficial to attend to the object cues (Experiments 1b and 2b). It was easier still to strategically shift attention to predictive face cues (Experiment 2c), indicating that the endogenous allocation of attention was augmented here by an additional effect. However, faces merely delayed the voluntary deployment of attention to object cues, but they could not prevent it, even at short cue-target intervals. This finding suggests that attention biases for faces can be rapidly countered by an observers endogenous control.

Me, Myself, and I: Different Recognition Rates for Three Photo-IDs of the Same Person

In all contemporary societies, photo-identity documents are used routinely for person identification, but this process is surprisingly fallible. Here we show that this problem is not limited to the identification of specific photographs of a person, but transcends three identity cards of the same person with different images. These identity cards varied substantially from each other in how well they could be recognised but identification rates were generally poor. We also present a potential solution to this problem by demonstrating that person identification can be improved when several photographs of the same person are made available.

Sex differences in unfamiliar face identification: Evidence from matching tasks.

Research on sex differences in face recognition has reported mixed results, on balance suggesting an advantage for female observers. However, it is not clear whether this advantage is specific to face processing or reflects a more general superiority effect in episodic memory. The current study therefore examined sex differences with a face-matching task that eliminates memory demands. Across two experiments, female but not male observers showed an own-sex advantage on match trials, in which two pictures have to be identified as the same person. This advantage was present for whole faces and when only the internal or external facial features were shown. Female observers were also more accurate in these three conditions on mismatch encounters, in which two photographs have to be identified as different people, but this reflects a more general effect that is present for male and female faces. These findings converge with claims of a female advantage in face recognition and demonstrate that this effect persists when memory demands are eliminated.

Scene and screen center bias early eye movements in scene viewing.

In laboratory studies of visual perception, images of natural scenes are routinely presented on a computer screen. Under these conditions, observers look at the center of scenes first, which might reflect an advantageous viewing position for extracting visual information. This study examined an alternative possibility, namely that initial eye movements are drawn towards the center of the screen. Observers searched visual scenes in a person detection task, while the scenes were aligned with the screen center or offset horizontally (Experiment 1). Two central viewing effects were observed, reflecting early visual biases to the scene and the screen center. The scene effect was modified by person content but is not specific to person detection tasks, while the screen bias cannot be explained by the low-level salience of a computer display (Experiment 2). These findings support the notion of a central viewing tendency in scene analysis, but also demonstrate a bias to the screen center that forms a potential artifact in visual perception experiments.

Gaze perception requires focused attention: evidence from an interference task.

The direction of another persons gaze is difficult to ignore when presented at the center of attention. In 6 experiments, perception of unattended gaze was investigated. Participants made directional (left-right) judgments to gazing-face or pointing-hand targets, which were accompanied by a distractor face or hand. Processing of the distractor was assessed via congruency effects on target response times. Congruency effects were found from the direction of distractor hands but not from the direction of distractor gazes (Experiment 1). This pattern persisted even when distractor sizes were increased to compensate for their peripheral presentation (Experiments 2 and 5). In contrast, congruency effects were exerted by profile heads (Experiments 3 and 4). In Experiment 6, isolated eye region distractors produced no congruency effects, even when they were presented near the target. These results suggest that, unlike other facial information, gaze direction cannot be perceived outside the focus of attention.

Revisiting the processing of internal and external features of unfamiliar faces: The headscarf effect

Five experiments are reported in which the relative importance of internal and external features for unfamiliar face identification are examined by a matching task. In experiments 1–3, Egyptian adults showed a robust internal-feature advantage for matching photographs of Egyptian faces. In experiment 4, a cross-cultural comparison between the ability of Egyptian and British adults to match the internal and external features of unfamiliar Egyptian and British faces was made. Once again, Egyptians showed an internal-feature advantage, for all faces. In contrast, British observers—and also Egyptian children in experiment 5—showed external-feature advantages consistent with previous research. We attribute this contrast to the long-term experience of Egyptians in perceiving and recognising faces with headscarves, which might develop more expertise in processing the internal than the external features of unfamiliar faces.