Abstract
A recent study about normal aging from our laboratory reported degraded face recognition across views but not with same views (Habak, Wilkinson, & Wilson, 2007, Vision Research). Therefore, we hypothesized that normal aging would affect face view adaptation. Younger (26 +/− 5.1 years) and older (67 +/− 5.2 years) subjects of 15 each with normal vision were recruited. They were required to make a two-alternative-forced choice of which direction a test face (200 ms) was facing after being adapted to an adapting face (5 s). Four adapting faces orientated at a side view (20°), an up view (20°), and their corresponding frontal views (for baseline measurement). Seven testing faces were orientated from left 6° to right 6° for side view and up 9° to down 9° for up or down view. The proportions of judging “right” or “down” view of 10 repetitions were calculated for each testing face at each condition. Point-of-subjective-equivalent (PSE) and sigma values were calculated from a psychophysical function. The older and younger groups showed similar baselines suggesting that thresholds of non-frontal view perceiving neurons are intact across aging. The older group showed a larger shift in PSEs and shallower slopes for the two adapting conditions suggesting that normal aging causes an increase in bandwidth of view-tuned neurons. These findings help to explain the degraded face perception in older population.
This work was supported by Post-doctoral fellowship, Ministry of Research and Innovation CIHR grant # 172103 to H.R.W.