Abstract
Horizontal orientations comprise the primary diagnostic structure for face perception (Dakin & Watt, J Vis 2009), and young adult observers’ ability to selectively use horizontal structure more than vertical structure (horizontal tuning) predicts both face identification accuracy and the face inversion effect magnitude (Pachai et al., Front Psychol 2013). Here, we ask if the age-related decline of face identification accuracy (Konar et al., Vis Res 2013) is associated with age-related changes in horizontal tuning. Because the N170 ERP component is delayed and smaller in response to faces lacking horizontal structure (Hashemi et al., VSS 2014), we also examined whether age-related behavioural changes in horizontal tuning were associated with age-related changes in both the N170 and the N250. We measured identification accuracy and ERPs in younger (M=22±3.8 years) and older (M=73±7.3 years) adults with a 6-AFC face identification task. Base stimuli were generated using a ±45 deg orientation filter centered on either the horizontal or vertical orientation, with additional stimuli generated by increasing orientation bandwidth by ±9 deg steps, totalling 10 orientation-filtered conditions plus 1 unfiltered condition that included all orientations. In younger observers, adding horizontal structure improved accuracy significantly more than adding vertical structure. However, in older adults, the addition of horizontal and vertical structure produced similar, small increases in accuracy. Thus, older adults exhibited less horizontal selectivity than younger adults. Interestingly, orientation filtering affected the N170 similarly in the two age groups, but the N250 was modulated by orientation filtering only in younger adults,consistent with the notion that the two ERP components represent different stages of face processing.The decreased behavioural horizontal tuning seen with age is reflected in the N250’s decreased sensitivity to orientation filtering, providing behavioural and electrophysiological support for the idea that face identification relies on effective use of horizontally oriented structure.
Meeting abstract presented at VSS 2015