Aging disrupts the neural transformations that link facial identity across views

Abstract

Healthy human aging can have adverse effects on cortical function and on the brain's ability to integrate visual information to form complex representations. Facial identification is crucial to successful social discourse, and yet, it remains unclear whether the neuronal mechanisms underlying face perception per se, and the speed with which they process information, change with age. We present face images whose discrimination relies strictly on the shape and geometry of a face at various stimulus durations. Interestingly, we demonstrate that facial identity matching is maintained with age when faces are shown in the same view (e.g., front-front or side-side), regardless of exposure duration, but degrades when faces are shown in different views (e.g., front and turned 20 degrees to the side) and does not improve at longer durations. Our results indicate that perceptual processing speed for complex representations and the mechanisms underlying same-view facial identity discrimination are maintained with age. In contrast, information is degraded in the neural transformations that represent facial identity across views. We suggest that the accumulation of useful information over time to refine a representation within a population of neurons saturates earlier in the aging visual system than it does in the younger system and contributes to the age-related deterioration of face discrimination across views.

Motion facilitates face perception across changes in viewpoint and expression in older adults.

“…As such, the results from Experiment 1 confirm previously reported findings that face matching performance de clines with age (e.g., Grady et al, 2000) and that this age-related cost is particularly apparent when matching facial identity across novel views of the face (Habak, Wilkinson, & Wilson, 2008). However, although older adults were overall worse at matching identity we noted that the cost on identity matching across views, which has previously been reported to be exacerbated by the ageing process, was evident only when the target face was pre sented as a sequence of three static images containing rigid changes (i.e., head rotation).…”

“…However, activation in this network was not suf ficient to support the matching of identity across views, as older adults who engaged this network did not reliably exhibit faster response times in this condition. Consistent with the conclusions drawn by Habak et al (2008), the results observed by Lee et al suggest that the ability to represent facial identity across different views diminishes with age and that this performance decrease likely emerges due to functional changes in the face processing network.…”

“…However, it is worth noting that other studies which have observed poorer viewpoint extrapolation in older age have examined matching performance across different viewpoints to those used in the current study. For example, Habak et al (2008) examined face matching between a 0° to 20 0 viewpoint, which may differentially affected perfor mance. In terms of RTs older adults were slower in matching facial identity than younger adults.…”

“…For example, Habak et al (2008) noted that compared with younger adults, performance in older adults was poorer when matching identities across changes in view. Moreover, they found that this cost in performance could not be reliably reduced in the older adult group by increasing the exposure duration of the target image, unlike in the younger adult group.…”

Visual Form Perception from Age 20 through 80 Years

“…[21][22][23] Age-related differences exist in the perception of shapes defined by texture, 24 and for higher levels of form processing, such as facial matching when faces are displayed from different viewpoints. 25 Previous studies that have documented age-related changes to form perception generally have included two age groups: younger adults (usually below ages 35 to 40 years) and older adults (typically over the age of 60 years), and have conducted detailed experiments on a specific aspect of form perception (e.g., orientation discrimination, 12 center-surround suppression of perceived contrast, 18,19 contour integration, 22 shape discrimination 26 ). Differing experimental designs among studies limit the ability to compare the relative magnitude of agerelated change across the many different aspects of form perception.…”