Motivational and emotional salience effects on working memory

“An object of primary memory is not thus brought back; it never was lost; its date was never cut off in consciousness from that of the immediately present moment. In fact, it comes to us as belonging to the rearward portion of the present space of time, and not to the genuine past.” (James, 1890, p. 609). Since William James’s seminal work on ‘primary’ memory, the notion that a short term memory store, now termed short term memory (STM) or working memory (WM) is a key part of human consciousness has become commonplace. This memory store is known to be subject to limitations in the amount and quality of information it can represent at any time, but is a crucial part of the cognitive toolkit humans use to navigate the physical and social world. Given these capacity limitations, there is a clear evolutionary imperative for efficient selection into and retention within WM of items of high utility over those of less importance to survival. Here, in a series of 9 behavioural and eye tracking experiments I investigate the cognitive mechanisms that serve to prioritise items of importance in WM, and the constraints and concomitant trade-offs that bound such processes. In particular, I focus on cognitive mechanisms by which ‘boosting’ of memory traces of motivationally important visual stimuli may be achieved, what factors cause stimuli to be treated as ‘motivationally salient’ in WM, and whether when one item gets ‘special treatment’ in WM this has impact on representation of other co-present stimuli. Experiments 1 through 5 investigate these phenomena with regard to faces bearing emotional expressions. Experiments 6 through 8 investigate whether learnt reward and punishment associations of faces affect their treatment in WM. Experiment 9 investigates whether motivational state per se can facilitate visual WM processes. While motivationally salient stimuli have long been known to produce shifts in selective attention (and indeed attention has been termed the ‘gatekeeper’ of WM), herein I provide evidence that selective attention is but one of the mechanisms by which stimuli of importance are accorded especially robust WM representations