Eiko Shimojo

Roles of familiarity and novelty in visual preference judgments are segregated across object categories

Understanding preference decision making is a challenging problem because the underlying process is often implicit and dependent on context, including past experience. There is evidence for both familiarity and novelty as critical factors for preference in adults and infants. To resolve this puzzling contradiction, we examined the cumulative effects of visual exposure in different object categories, including faces, natural scenes, and geometric figures, in a two-alternative preference task. The results show a clear segregation of preference across object categories, with familiarity preference dominant in faces and novelty preference dominant in natural scenes. No strong bias was observed in geometric figures. The effects were replicated even when images were converted to line drawings, inverted, or presented only briefly, and also when spatial frequency and contour distribution were controlled. The effects of exposure were reset by a blank of 1 wk or 3 wk. Thus, the category-specific segregation of familiarity and novelty preferences is based on quick visual categorization and cannot be caused by the difference in low-level visual features between object categories. Instead, it could be due either to different biological significances/attractiveness criteria across these categories, or to some other factors, such as differences in within-category variance and adaptive tuning of the perceptual system.

Don't look at the eyes: Live interaction reveals strong eye avoidance behavior in autism

Atypical social gaze is commonly observed in individuals with autism (ASD) in real-world and clinical settings. Laboratory tasks using social stimuli have shown reduced gaze to face and eyes and reduced social orienting in high-functioning adults compared to neurotypical (NT) controls, although differences were often marginal, perhaps due to static stimuli or non-interactive tasks. In this study, we investigated gaze during live, naturalistic interactions between pairs of participants conversing freely about their interests, while gaze and video were recorded for both. Results from 8 NT and 7 ASD participants revealed distinct gaze patterns, distinguishing the groups. All NT participants displayed a consistent pattern of high gaze frequency and duration (mean=54%) to the eyes and low gaze to the mouth (mean=1%). ASD participants showed significantly lower gaze frequency (mean=10%, p< 0.00000001) and duration (mean=7%, p< 0.000001) to the eyes, with higher frequency (mean=33%, p< 0.02) and duration (mean=39%, p< 0.02) to the mouth, and no difference for the face (NT mean=77%, ASD mean=72%, n.s.). Only NTs showed a significant preference for the left eye in frequency (p< 0.05) and duration (p< 0.04). Mouth gaze split ASD participants into subgroups of high (N=4) or low (N=3) frequency, but long mouth fixations characterized ASD overall (640 ms) and distinguished (p< 0.01) from short fixations (210 ms) in NT. Together, these results show that live, interactive experiments can detect striking differences in social gaze between NT and ASD groups. The NT pattern is defined by high eye contact with occasional, passing glances at the mouth, while ASD shows a strong, spontaneous tendency to avoid the eyes and prolonged fixations to the mouth. Diversion of gaze to the mouth or other face regions (e.g. nose, cheeks, forehead) suggests a compensatory mechanism for eye avoidance that allows face gaze without direct eye-to-eye contact in ASD. Meeting abstract presented at VSS 2015.