Graduation Year


Document Type




Degree Name

Master of Arts (M.A.)

Degree Granting Department


Major Professor

Chad Dubé, Ph.D.

Co-Major Professor

Kenneth Malmberg, Ph.D.

Committee Member

Elizabeth Schotter, Ph.D.

Committee Member

Kristen Salomon, Ph.D.


ensemble averaging, summary perception, memory, perception, visual processing, visual gist


The aim of the current work was to determine the amount of information that contributes to the formation of summary statistical representations (SSRs), as well as the time course over which these representations are formed. While the prevailing interpretation of SSRs within literature is that the summaries are formed through a compulsory rapid integration across all information in a scene, debate exists on the necessity of this unique processing mode. To investigate the formation of SSRs, two experiments were conducted. In the first, results from an orientation averaging task were compared to results from a whole-report task, over equivalent stimulus displays. The purpose of this experiment was to determine if items reported in a visual short-term memory (vSTM) task could predict responses on an orientation averaging task, to inform a likely set of items that contribute to SSRs. The second experiment was conducted to determine whether SSRs are generated by a time dependent process, and the rate at which information is accumulated into the averaging process. This experiment consisted of conducting an orientation averaging task on masked or unmasked displays, with variably brief exposure durations. Results indicated that SSRs are predicted by whole-report responses, and follow a pattern of temporal results consistent with encoding information into vSTM. Together, the results provide evidence against a unique early summarization process, and instead indicate an averaging control process acting on items within vSTM. The results were incorporated into a simple computational model of the SSR generation process.