| dc.description.abstract | We use visual working memory to temporarily store visual information about our environment. However, our environment is mostly visually static and as such, memory can often be ‘offloaded’ onto the environment. This leads to a trade-off between choosing to internally store information or to externally sample it. In this thesis we explored how this storage/sampling trade-off changes as reliability of access to the environment changes, by submitting participants to a copying task. In this task, participants were instructed to copy a layout of stimuli on the left side of a computer screen to the right side of the screen. The example layout intermittently appeared and disappeared throughout a trial, the timing of which we varied across conditions. We found that, as the example layout disappeared for greater amounts of time, participants sampled it less often (and thus likely memorised more items at once) than in the baseline condition, in which the example layout was always visible. We then designed and ran a computational cognitive model, with which we attempted to simulate the participants’ behaviour in such a way that that we could compare the model’s results to behavioural observations. The model explored different combinations of possible strategies, namely regarding the number of stimuli it attempted to remember with each gaze toward the example layout, and regarding how many times a stimulus was rehearsed in memory after its first encoding. We then compared human data and model data on three outcome variables: (1) the number of crossings from the right side of the screen to the example layout on the left side; (2) the completion time of trials; and (3) the number of fixations per second. A model was found that fits well to participants’ completion time and number of fixations per trial, but less strongly on the number of crossings per trial. Our findings suggest that there may indeed occur a shift in in the usage of visual working memory when reliability of visual access changes, which leads us to believe a storage/sampling trade-off also exists in environments with varying reliability of visual access. We conclude by recommending that future research endeavours take into account a storage/sampling trade-off in conditions with varying reliability of visual access. | |
