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Online or offline? Exploring working memory constraints in spatial updating

Harrison, Anthony M (2008) Online or offline? Exploring working memory constraints in spatial updating. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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All spatial representation theories rely upon two spatial updating processes in order to maintain spatially consistent self-to-object relationships: movement-driven, automatic online updating and offline, conscious mental transformations of perspective. Theoretical differentiation based on offline updating is difficult given the equivalent predictions for many of the spatial tasks commonly used (i.e. egocentric pointing). However, representational theories do diverge with respect to the predicted working memory constraints of online updating. In experiment one participants studied groups of 4, 6, & 8 targets, engaged in a 180º rotation on half the trials and completed a series of judgments of relative direction and egocentric pointing. Set size effects for both tasks were limited to latencies alone, suggesting offline updating. Experiment two had participants study smaller (3 target) configurations and make egocentric pointing responses. On half the trials, participants engaged in either a verbal or spatial 1-back task during both retention and rotation periods. No effect of dual-task load or type were found for egocentric pointing. Both latencies and errors were significantly greater for the post-rotation pointing suggesting offline updating. The lack of evidence for online updating is surprising and contrary to previous findings that it is an obligatory automatic process (e.g. Farrell & Thomson, 1998). Multiple models were developed within ACT-R/S (Harrison & Schunn, 2003) illustrating the sufficiency of offline updating to account for the current findings. The challenges of detecting online updating and investigating its working memory constraints are discussed in the light of these results and simulations.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Harrison, Anthony
Date: 24 January 2008
Date Type: Completion
Defense Date: 14 September 2007
Approval Date: 24 January 2008
Submission Date: 25 September 2007
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Psychology
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: ACT-R; allocentric; cognitive modeling; egocentric; judgment of relative direction; spatial reasoning; spatial updating
Other ID:, etd-09252007-142625
Date Deposited: 10 Nov 2011 20:02
Last Modified: 15 Nov 2016 13:50


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