Award Date


Degree Type


Degree Name

Master of Arts (MA)



First Committee Member

Colleen Parks

Second Committee Member

David Copeland

Third Committee Member

Joel Snyder

Fourth Committee Member

Lisa Bendixen


Recent theories of forgetting posit that hippocampally-based memory representations are more prone to be forgotten due to decay, while extra-hippocampal representations are more likely to be forgotten due to interference (Hardt, Nader, & Nadel, 2013; Sadeh & Pertzov, 2020). The current study examined this hypothesis by comparing the rate of forgetting between pattern separation, a hippocampally-based process, and item recognition, a process that is reliant on both hippocampal and extra-hippocampal structures. It was hypothesized that pattern separation would display more forgetting due to decay because it is a hippocampally-based process, while item recognition would display more forgetting due to interference since its processes are extra-hippocampally-dependent. Participants were tested over five consecutive days using the Mnemonic Similarity Task (Stark & Kirwan, 2019), an object recognition task that yields estimates of pattern separation and item recognition. Additionally, Wickelgren’s model (1975) was fit to the data to estimate forgetting rate due to decay and interference. Results indicate that pattern separation showed more forgetting due to decay, while item recognition showed more forgetting due to interference, supporting the current hypothesis. At the group level, Wickelgren’s model was able to fit the observed data and predicted future forgetting quite well. Importantly, the current study adds to the growing body of literature on forgetting and can be used to clarify mixed findings within the literature.


Familiarity; Forgetting; Human Memory; Pattern Separation; Recognition Memory; Recollection


Cognitive Psychology

File Format


File Size

562 KB

Degree Grantor

University of Nevada, Las Vegas




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