Date of Award

Summer 8-1-2018

Author's School

Graduate School of Arts and Sciences

Author's Department


Additional Affiliations

Psychological & Brain Sciences: Brain, Behavior, & Cognition

Degree Name

Master of Arts (AM/MA)

Degree Type



Kahneman’s (1973) cognitive load theory assumes that time pressure-induced arousal is a major contributor to pupil dilation during cognition. In contrast, current pupillometry research has failed to consider the possible role of time pressure during encoding, instead often assuming that encoding dilations may track the elaborative or information processing aspects of successful memory creation. Here we focus on dilation during memory encoding as the current literature yields mixed results, with pupillary dilation sometimes being linked to subsequent recognition success and other times to subsequent recognition failure. To dissociate the nature of elaborative processing from incurred decision time pressure, we collected pupillary dilations while crossing depth of processing (shallow vs. deep) with time pressure (fast vs. slow), using a subjective response deadline procedure. There were three main findings.

As expected, subjects responded more quickly in the speeded condition and subsequent recognition was considerably higher for items that were deeply versus shallowly encoded. Interestingly, speeding encoding judgments did not impair subsequent recognition performance.

Second, pupillometry results indicate that on average, shallow processing yielded greater dilation than deep processing, and speeded judgments yielded greater dilation than non-speeded judgments. However, these main effects were conditioned by an interaction, such that the greater dilation for shallow versus deep processing was amplified with greater time pressure. Subsequent analyses demonstrated that the greater dilation during the shallow task was mainly the consequence of slower responding, and thus accruing time pressure to come to a decision, during that task. Thus the dilation response during encoding was insensitive to differences in the nature of elaboration but highly sensitive to the degree of time pressure incurred during judgment.

Finally, in terms of subsequent recognition outcomes, the data revealed a subsequent forgetting pattern. That is, increased dilation during encoding (collapsed across all conditions) was associated with later recognition failure, not recognition success. Confirming the time-pressure interpretation, subsequent misses were also associated with slower judgments at encoding than subsequent hits.

These findings suggest that Kahneman’s original emphasis on time pressure in the conceptualization of cognitive load should again be highlighted. Our work shows that rather than providing evidence for successful memory creation, pupillary dilations at encoding appear to primarily be indicative of judgment time pressure.


English (en)

Chair and Committee

Ian G. Dobbins

Committee Members

David Balota, Todd Braver


Defended on May 17, 2018

Available for download on Sunday, December 17, 2045