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Out of sight, not out of mind : visual processing and immediate memory


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Hecker, Robert A 1996 , 'Out of sight, not out of mind : visual processing and immediate memory', PhD thesis, University of Tasmania.

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The following thesis details 15 experiments using computer generated
stimuli and extending the known aspects of perception to the early stages of
visual information processing.
A standard procedure in information processing is to use a backward
masking paradigm to limit the amount of time for which the stimulus is
available. Initial experiments established that a secondary non-visual task
which required active attention increased the time required for correct
discriminations while secondary unattended stimuli did not. These
divergent findings were evaluated in conjunction with other theoretical
considerations and re-analyses of existing data. It was concluded that,
contrary to previous assumptions, the backward masking procedure was
primarily reflecting factors such as strategy use rather than
speed-of-processing per se.
An alternative paradigm for investigating the nature of visual
information processing is to present a series of stimuli which must be
reported. Previous attempts to infer the structure and nature of the
processes involved have typically used interference from secondary tasks
which require conscious effort or attention. The use of any dual-task
paradigm is confounded by difficulty in separating out the involvement of
general-purpose resources. A,major concern of the subsequent experiments was to investigate whether it was possible to selectively impair performance
by irrelevant peripheral stimuli. Initial experiments established that this
could be done and that the presence or absence of interference was altered by
changes in the target or surround in a fashion not predictable from their
overt similarities. Rather, it is argued, they are explicable only in terms of
whether or not common visual subsystems were involved. These
conclusions were supported by experiments which yielded a successful
double dissociation between the location and object characteristics (both
colour and pattern) of the task.
In conclusion it is argued that a sound appreciation of the underlying
visual mechanisms is essential to the understanding of the early stages of the
processing of visual information. In the earlier stage this approach has led to
a re-evaluation of a widely accepted paradigm, in the latter portion it has led
to support for the notion that spatial and object characteristics are coded and
stored separately. Implications of this approach in other areas are discussed.

Item Type: Thesis - PhD
Authors/Creators:Hecker, Robert A
Keywords: Memory, Human information processing, Imagery (Psychology), Visual perception
Copyright Holders: The Author
Additional Information:

Thesis (Ph.D.)--University of Tasmania, 1997. Includes bibliographical references

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