In theme 1 of this project we explored how our decision making processes are adapted to different contextual demands. In a first project we examined how decisions are made when the timing and location of relevant sensory information is unpredictable. We showed that under such circumstances the brain relies on rapid visual responses evoked by target stimuli to trigger the evidence gathering process (Loughnane et al 2016, Curr Biol; Neweman et al 2017, J Neurosci; Devine et al 2018, eLife). Such processes had not previously been implicated in decision making and point to an important new avenue for future research. In a second project we examined how our decisions are adapted to meet time pressure demands. We showed that the brain employs a number of distinct adjustments including boosting the visual representation of relevant information, lowering the quantity of evidence needed to commit to a decision and an acceleration of the decision-reporting motor acts. These results, reported in Steinemann et al (2018, Nat Comms) reveal that the neural adjustments to time pressure are more diverse than the dominant models of decision making had suggested. In a further investigation we developed a new decision model which took account of these neural observations (Kelly et al, in press, Nat Hum Beh).
In theme 2 of this project we sought to establish how choice confidence is represented in the brain. We showed that the same neural evidence accumulation signals that contribute to our choices, continue to accumulate evidence after the choice has been made and this 'post-decisional' accumulation plays a critical role in facilitating error detection (Murphy et al, 2015, eLife). We capitalised on these discoveries to provide new, more detailed insights into the impact of natural aging on metacognition (Harty et al 2017, Neuroimage). Further studies examining relationships between laboratory based tests of choice confidence and real-world metrics of cognitive performance have been completed and a manuscript is being prepared.
In theme 3 of this project we examined in detail how natural aging impacts on decision making processes. A review of the literature by our group established that this has been a relatively understudies area and, in particular, neurophysiological analyses were lacking (Dully et al, 2018, Beh Brain Res). We ran a multi-experiment study on a group of older and younger adults who performed a set of perceptual decision making tasks. We fit a conventional model of decision making to their behavioural data and found effects that accorded with those commonly reported in the literature - most prominently that elderly individuals respond more slowly on cognitive tasks due to implementing a more conservative decision making strategy. However, accompanying neurophysiological analyses produced conflicting results, finding no differences in the quantity of evidence old versus young adults required to commit to a decision. We therefore developed a novel model that took into account our neural observations and it yielded important new insights. First, it indicated that older adults on average tended to accumulate evidence less efficiently on some, but not all, perceptual tasks. Most interestingly, the model also highlighted that older adults were better at maintaining attention throughout the task. Thus the model pointed to both positive and negative aging effects on perceptual decision making. The results were reported in McGovern et al (2018, Nat Hum Beh).
