Visual exploration of facial emotion by healthy older adults and patients with Alzheimer disease

Objective: The purpose of this study was to investigate eye movement patterns of patients with Alzheimer disease (AD) and healthy older adults while viewing photographs of facial expression. Background: Individuals with Alzheimer disease appear to have deficits in emotion perception, but the underlying mechanisms are not understood well. It is not known whether individuals with AD visually explore facial stimuli and extract information needed to make emotion identification from faces in the same way as do healthy older adults. Method: Seventeen AD patients and 15 older adult control patients were shown faces that depicted different emotions and were asked to identify the emotion displayed from two alternatives. The eye movements of participants were recorded during the emotion identification task. Results: No differences were seen between AD patients and older adult controls regarding their accuracy of emotion identification. However, AD patients differed from older adult controls on eye movement patterns during the emotion identification task. Alzheimer disease patients fixated less on the face and, in particular, on the eyes. Alzheimer disease patients also spent more time viewing areas off the face. There was no relationship between the severity of cognitive impairment and emotion identification or eye movement patterns, Conclusions: Although the AD patients and older adult controls showed similar accuracy for the emotion identification task, their visual processing strategies differed. Relative to older adult controls, AD patients fixated less on discriminating regions and attended more to irrelevant aspects of stimuli. The eye movement differences were particularly evident in AD patients who did more poorly for the emotion identification task. These differences were not attributable to the global cognitive deterioration accompanying AD: but suggested a specific deficit in visual processing abilities.