Younger adults’ perception of and attention to facial stimuli are enhanced by positive and negative emotional expressions, with negativity leading to a greater benefit than positivity. Conversely, older adults demonstrate a positivity bias, devoting more attention to positive stimuli and less to negative. It is unclear if age differences in these attentional preferences emerge due to differences in how their perceptual systems respond to positive and negative stimuli. Emotional facial expressions elicit enhanced P1 and N170 components of visually-evoked event-related potentials (ERP) over posterior scalp regions associated with vision. The current study examined the extent to which angry and happy facial expressions evoked differential patterns of P1 and N170 enhancements in younger (n = 21, ages 18-30) and older (n = 20, ages 60-76) adults. Participants were presented with happy, angry, and neutral faces under four instructional conditions: passively view, passively view but consider emotion, categorize emotion, and categorize gender. ERPs were recorded from the posterior scalp electrodes of a 128- channel high density electrode array and were time-locked to the onset of facial stimuli. The recordings were segmented and averaged based on the instructional condition and emotional expression of the stimulus. Analyses of the average P1 and N170 latencies revealed no age differences. Overall, participants displayed larger amplitude P1 and N170 to all stimuli when asked to categorize gender or emotionality. Contrary to expectations, both younger and older adults displayed larger N170 amplitudes for angry
and happy expressions relative to neutral ones. Although older adults display a positivity bias in allocating attention to emotional stimuli, in the current study, younger and older adults both displayed an enhanced N170 for emotional faces relative to neutral faces, suggesting that the perceptual systems of younger and older adults are similarly engaged in processing positive and negative facial expressions at early time points.
| Identifer | oai:union.ndltd.org:WKU/oai:digitalcommons.wku.edu:theses-2483 |
| Date | 01 May 2015 |
| Creators | Chambers, Nicole Elaine |
| Publisher | TopSCHOLAR® |
| Source Sets | Western Kentucky University Theses |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Masters Theses & Specialist Projects |
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