Missing, wanted, lost
: the effects of perceptual information on prospective person memory

Student thesis: Doctoral Thesis


When a person goes missing, the police or other non-governmental organizations usually distribute appeals asking the public to be on the lookout for that individual and to report any sighting to the authorities. Social scientists have conceptualised this process as a prospective person memory task, and used experimental designs to highlight some of its difficulties (Lampinen et al., 2009). The overarching aim of this thesis was to find ways of improving performance on this task, particularly focusing on manipulating the information provided during encoding. Specifically, I examined the effects of increasing the amount of perceptual and conceptual information on prospective person memory. In Experiment 1 (Chapter 2), I looked at the effects of within-person variability and names on prospective person memory. Previous studies showed that increasing the amount of within-person variability seen during encoding improves unfamiliar face learning. Using high variability images (i.e., from different contexts) improved prospective person discriminability in comparison with using low variability images (i.e., from the same context). Associating images of previously unfamiliar people with their names also improved discriminability.
In Experiments 2 and 3 (Chapter 3), we replicated the effect of within-person variability. In these two experiments we wanted to see whether the way multiple images are presented interacts with the effect of increased image variability. Therefore, in these experiments the three images of each target were presented simultaneously, massed sequentially or distributed sequentially. Presentation mode did not affect PPM performance, and it did not consistently interact with the effect of variability. In Experiment 4 (Chapter 4) I focused on the effect of contextual information on prospective person memory. Participants learned each target face along with their name only (i.e., control condition), their name and some contextual information that matched the way they were encountered during testing (i.e., relevant context condition), or their name and some contextual information that did not match the way they were encountered during testing (i.e., irrelevant context condition). Learning the contextual information did not affect participants’ performance in comparison with knowing target’s name only. In Chapter 5, I discuss implications of this research for theories of face recognition, prospective memory and attention, and practical implications of our research findings for missing people searches and for wanted criminal investigations.
Date of AwardAug 2021
Original languageEnglish
Awarding Institution
  • University of Portsmouth
SupervisorHartmut Blank (Supervisor), Ryan Joseph Fitzgerald (Supervisor), Lorraine Hope (Supervisor) & James Alexander Ost (Supervisor)

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