Abstract
Emotion recognition is key to social functioning, though it declines across the adult lifespan. Why decline occurs and how it should be addressed is yet to be understood. In this thesis I investigated potential causes of emotion recognition decline, as well as the efficacy of a novel music training intervention with older adults to improve emotion recognition. I put forth in the Introduction the argument that age-related declines in emotion recognition are primarily caused by neurodegeneration, and that because music training is a uniquely powerful stimulus for facilitating neuroplasticity, musical engagement in older adulthood should improve neuropsychological functioning by attenuating neurodegeneration, particularly in the frontal lobes.
In Study 1, young (aged 18 to 30 years) and older adults (aged 59 years and older) completed laboratory tasks assessing facial and musical emotion recognition, facial age estimation, fluid intelligence, and musical competence. During all but the musical competence task, surface-level activity in the medial and lateral prefrontal cortex (PFC) was monitored using functional near-infrared spectroscopy. Older adults performed more poorly on the musical emotion task relative to young adults, and this was not due to having worse musical competence or cognitive ability. Face processing decline also did not appear to cause emotion recognition difficulties among older adults, as performance on the two face tasks were not correlated. Older adults also showed greater left and right lateral PFC activation during the two emotion tasks compared to young adults, and a contrast between the two emotion tasks within the older group revealed greater music-related than face-related activation in the lateral regions. Neurodegeneration was the most compelling explanation of the findings. Older adults appeared to require greater activation in cognitive control areas to compensate for neurodegeneration, proportionate to task difficulty.
In Study 2, the older adults who participated in Study 1 were randomly assigned either to a four-month, group-based music appreciation or guitar learning intervention designed specifically for this research. After the intervention, participants completed the same tasks as outlined above, again, while cortical PFC activity monitored. Facial and musical emotion recognition improved between pre- and post-intervention, collapsing across both groups, but I did not find evidence for a relative benefit of one intervention over the other on the behavioural or neuroimaging measures. However, older adults’ age moderated the effect of intervention group on changes in behavioural musical emotion recognition and PFC activation during facial emotion recognition. For guitar learners but not music appreciators, advancing age was associated with greater improvements in musical emotion recognition and increases in facial emotion-related PFC activation. Guitar learning, thus, promoted emotion recognition for those at ages where neurodegeneration has had its greatest impact.
The implications of Study 1 and Study 2 and their relation to previous research are examined in the General Discussion. Overall, the take-home message is this: we should look to brain health to both understand and improve older adults’ emotion recognition, and music training is a suitable vehicle to do so.