Cognitive and neural factors underlying the manipulation of visual memory representations

Goal-directed behaviour relies on the ability to store relevant information in visual shortterm
memory (VSTM) and to briefly maintain its representation for manipulations (Visual
Working Memory, VWM). Crucial cognitive processes for this ability include perceptual
encoding, maintenance and retrieval of task-relevant stimuli, as well as selectively suppress taskirrelevant
information. Despite the relevance of these processes is known, their combined and
individual contribution is less clear, as well as the specific role of the initial perceptual accuracy
and individual variability in manipulating information held in memory.

This thesis addresses these issues by examining the cognitive and neural processes
underlying the maintenance of memory representations for short intervals.

In the first part of this work, we used a novel behavioural paradigm to study the role of
perceptual accuracy as well as of the combined and individual contribution of other cognitive
factors underlying visual short-term memory. A second study extended the investigation to the
maintenance period, providing task-based and endogenous electrophysiological correlates of
successful maintenance.

The second part of this thesis used a retro-cue based WM paradigm to investigate the
attentional and inhibitory mechanisms involve in the maintenance process, and required when
manipulating stored information. Considering the vulnerability of these processes in healthy
ageing, the investigation is also extended to an older sample.

This last part of the thesis provided cognitive and neural results that reconciled
contrasting findings on the WM literature based on retro-cue. Specifically, a novel concept of
cognitive flexibility and its electrophysiological predictors are proposed to underlie individual
variability in manipulating memory representation.