Contrast reversal of the iris and sclera increases the face sensitive N170.

Previous research has demonstrated that reversing the contrast of the eye region, which includes the eyebrows, affects the N170 ERP. To selectively assess the impact of just the eyes, the present study evaluated the N170 in response to reversing contrast polarity of just the iris and sclera in upright and inverted face stimuli. Contrast reversal of the eyes increased the amplitude of the N170 for upright faces, but not for inverted faces, suggesting that the contrast of eyes is an important contributor to the N170 ERP.

Early and late event-related potentials are modulated by infant and adult faces of high and low attractiveness.

The processing of infant faces may be somewhat distinct from that of adult faces. Indeed, recent neuroimaging studies have provided evidence of an early, "baby-specific" neural response whereby infant faces are perceived more rapidly than adult faces. Using event-related potentials, the present study aimed to determine whether the preferential response to infant faces is present at both early and late stages of face processing, and to investigate the effects of esthetic appearance on the processing of adult and infant faces by directly manipulating the perceived attractiveness or cuteness within a given face identity. Here, we find evidence for enhanced processing of infant faces, relative to adult faces, at both early (N170, P2) and late (LPC) stages of face processing. We also find that the esthetic appearance of both infant and adult faces modulates early neural responses, with enhanced responses to less attractive/cute faces as compared to more attractive/cute faces. Overall, our results provide additional evidence for a preferential response to infant faces at early stages of processing, and provide new evidence that this preferential response occurs at later stages of face processing as well, independent of the esthetic quality of the face or observer sex.

Dorsal stream activity and connectivity associated with action priming of ambiguous apparent motion.

Theories proposing a bidirectional influence between action and perception are well supported by behavioral findings. In contrast to the growing literature investigating the brain mechanisms by which perception influences action, there is a relative dearth of neural evidence documenting how action may influence perception. Here we show that action priming of apparent motion perception is associated with increased functional connectivity between dorsal cortical regions connecting vision with action. Participants manually rotated a joystick in a clockwise or counter-clockwise direction while viewing ambiguous apparent rotational motion. Actions influenced perception when the perceived direction of the ambiguous display was the same as manual rotation. For comparison, participants also rotated the joystick while viewing non-ambiguous apparent motion and in the absence of apparent motion. In a final control condition, participants viewed ambiguous apparent motion without manual rotation. Actions influence on perception was accompanied by a significant increase in alpha and beta band event related desynchronization (ERD) in contralateral primary motor cortex, superior parietal lobe and middle occipital gyrus. Increased ERD across these areas was accompanied by an increase in gamma band phase locking between primary motor, parietal, striate and extrastriate regions. Similar patterns were not observed when action was compatible with perception, but did not influence it. These data demonstrate that action influences perception by strengthening the interaction across a broad sensorimotor network for the putative purpose of integrating compatible action outcomes and sensory information into a single coherent percept.

Thatcherization impacts the processing of own-race faces more so than other-race faces: an ERP study.

It has been suggested that differential use of configural processing strategies may underlie racially based recognition deficits (known as the "other-race effect"). By employing a well-known configural manipulation (Thatcherization, i.e., rotating the eyes and mouth by 180°), we aimed to demonstrate, electrophysiologically, that configural processing is used to a greater extent when viewing same-race faces than when viewing other-race faces. Face-related event-related potential (ERP) responses were measured for participants viewing normal and Thatcherized faces of their own race (Caucasian) and of another race (African-American). The P1 and N170 components were modulated to a greater extent by Thatcherization for same-race faces, suggesting that the processing of these faces is, in fact, more reliant on configural information than other-race faces. Thatcherization also affected the P250 component more so for same-race faces independently of orientation. The race-dependent effects of Thatcherization as early as P1 suggest that configural encoding may be occurring much earlier than the well-cited N170.

Take a look at the bright side: effects of contrast polarity on gaze direction judgments.

Observers are inaccurate when judging the gaze direction of eyes shown in negative rather than positive polarity. On the basis of this polarity effect, it has been proposed that gaze is perceived as directed from the dark part of the eye. Our experiment investigated whether direction judgments simply follow this heuristic, as has been suggested. Participants judged the gaze direction of eyes shown at different eccentricities in positive or negative polarity. The error pattern revealed that most errors were incorrect "straight" judgments, suggesting that judgments do not merely follow the heuristic "the dark part does the looking." We suggest that gaze judgments are based on the outcome of a competition between gaze direction signals: Whereas luminance cues may indicate that gaze is directed from the dark part of the eye, geometric cues may indicate the opposite. This interpretation is supported by reduced overall error rates, and fewer incorrect "straight" responses, for more extreme gaze directions.

What are you looking at? Acuity for triadic eye gaze.

The authors measured observers' ability to determine direction of gaze toward an object in space. In Experiment 1, they determined the difference threshold for determining whether a live "looker" was looking to the left or right of a target point. Acuity for eye direction was quite high (approximately 30 s arc). Viewing the movement of the looker's eyes did not improve acuity. When one of the looker's eyes was occluded, the observers' acuity was disrupted and their point of subjective equality was shifted away from the exposed eye. Experiment 2 was a replication of Experiment 1, but digitized gaze displays were used. The results of Experiment 3 showed that the acuity for direction of gaze depended on the position of the looker's target. Overall, the results indicated that humans are highly sensitive to gaze direction and that information from both eyes is used to determine direction of regard.