• The Mental Representation of Visual Information

      Robitaille, Joel; Department of Psychology
      Despite working in relative independence, the working memory and imagery literatures investigate the mental representation of visual information. Recent reports investigating the neural structure and their associated functional activity responsible for the creation and maintenance of these cognitive representations suggest a significant overlap between these fields of study. Because each field has adopted methodologies that does not allow for a direct comparison of the mental representation described by their respective literatures, it is difficult to determine whether imagery and working memory representations are related. Hence, the current thesis further investigates the properties of the visual representation of visual information to bridge between the imagery and working memory fields. In a first study, I compare the psychophysical properties of simple stimuli commonly used in working memory reports with more complex objects adopted by the imagery field. In the course of three experiments, I demonstrate that the cost of stimulus complexity predominantly affects the quality of the mental representation while still providing evidence of a shared cognitive mechanism driving the formation and maintenance of these representations. In a second study, I evaluate the impact of mental rotation on these mental representations as well as whether the adoption of different paradigms, along with different performance metrics, assess the same cognitive construct. Here again, I show strong evidence in support of a common cognitive mechanism driving the performance across mental manipulation and through assessment methods. Finally, the last study attempted to track the manipulation of these visual representations by applying an encoding model to raw EEG activity. While I show evidence of the orientation-relevant activity during perception, the encoding model does not detect reliable enough activity to allow for tracking the orientation of the stimulus during retention and mental rotation. Together, this thesis provides evidence of a shared cognitive mechanism that drives visual working memory and imagery representation, but tracking these mental representations using EEG activity during manipulation remains unclear.