Using Pupil Dilation to Investigate False Memories of Semantic Associates

Previous false memory research has found that lists of words with phonological associates will produce significant false memory effects for recall and recognition. For example, when participants listen to a list of phonological associates to the word “cat”—such as “that,” “fat,” and “cab”—they often report that they remember hearing the word “cat,” despite the fact that they have not listened to that word. The present study replicated Sommers & Lewis (1999) false memory research, expanding on their investigations by employing the measure of pupil dilation. Pupil dilation measurements were used in order to consider false memory effects in conjunction to “pupil old/new” effects; these effects explain how a person’s pupils will respond to stimulus words—after listening to a list of words, people’s pupils dilate when they listen to a previously heard (“old”) word, but not when they listen to an unheard (“new”) word. We hypothesized that the “pupil old/new” effect would also occur for falsely remembered words, which we tested using an Eyelink 1000 eye-tracker. The addition of the pupil measurements allowed us to address a concern that previous false memory research has not had the capacity to consider: we were able to distinguish listener responses to veridical words (words they had heard) from critical items (words they had not heard). The results showed that there is a significant difference in the Pupil Dilation Ratio (PDR) when participants previously heard a word compared to when they incorrectly recalled a word due to false memory. We also found that the pupil effect is greater only when participants had the (false) subjective experience of having heard the word. In Spring 2018, we will continue collecting data and create a follow-up experiment using semantic associates to test for pupil dilation in response to false memory