Distraction by unintentional recognition: Neurocognitive mechanisms and modulations by ageing

Previous research has suggested that aging is associated with increased distractibility and

impaired intentional retrieval processes. I investigated potential age differences in the

effect of unintentional recognition of to-be-ignored distractor images on intentional

recognition decisions to targets words, and the brain processes that are associated with

unintentional versus intentional recognition. This research involved comparing old (60-76)

and young (18-24) adults' performance and brain activity during a Memory Stroop task,

analysing behavioural data (accuracy and reaction times), event-related potentials (ERPs)

and induced and evoked EEG oscillations in the theta and alpha bands. At the behavioural

level, the older group exhibited the expected poorer intentional recognition memory for

targets, but the biasing effect of unintentional distractor recognition on target decisions was

very similar across age groups. In the ERP domain, the older group showed much reduced

or absent ERP effects related to 'familiarity' and 'recollection' that were strongly

expressed in the younger group. Furthermore, the older group showed a reversal of typical

old/new ERP effects for targets, suggesting that they engaged a qualitatively different

neurocognitive process during intentional recognition. This effect may reflect a

compensatory mechanism that is used as part of an adaptive strategy to address age-related

declines in the brain processes used by young adults to solve the task. However, broadly

similar patterns of old/new differences in theta and alpha power were found across both

age groups for both intentional target recognition and unintentional distractor recognition.

Overall, the results show novel evidence of how the neural correlates of recognition

memory are affected by aging and intentionality, and suggest that future research should

employ both ERP and oscillation analysis of EEG data to better understand neurocognitive

aging.