Degree Type


Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Gary Wells


Research regarding the evaluation of alibis has been sparse to date. The current experiments were designed to assess how people evaluate and process alibi statements. It was hypothesized that people approach alibis with skepticism and that alibis elicit different processing from evaluators than do everyday memory statements. Experiment 1 used a cognitive busyness paradigm to assess the starting point from which alibi evaluators begin. Results indicated the cognitive busyness manipulation did not affect participants' ratings of believability of either the weak or strong alibi. The superficial evaluation hypothesis was advanced as a potential explanation for the ineffectiveness of the busyness manipulation---that participants who were cognitively busy were interrupted in their processing of the central facts of the case but were nonetheless able to use simple, peripheral cues to arrive at similar evaluations as non-cognitively-busy participants. Experiment 2 manipulated the timing and type of alibi schema to examine whether alibis are processed differently from a normal narrative story. All participants viewed the same narrative account; some participants knew prior to viewing that the account was an alibi whereas others discovered after viewing that the account was an alibi. In addition, some participants were told the guilt or innocence status of the alibi provider. Results indicated that when participants did not know the ultimate status of the alibi provider and knew that they were viewing an alibi prior to watching the alibi video, their recall was biased toward details occurring during the time period most relevant to the alibi. Knowledge that the account was an alibi affected participants' encoding, but not retrieval, of the alibi story. There was no clear support for the hypothesis that alibi evaluators approach alibis with skepticism, but there was support for the hypothesis that people encode alibi information differently than they encode an everyday narrative account.



Digital Repository @ Iowa State University,

Copyright Owner

Elizabeth Ann Olson



Proquest ID


File Format


File Size

74 pages