Differential visual short term memory performance between young and healthy older adults
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Date
30/06/2015Item status
Restricted AccessEmbargo end date
31/12/2100Author
Horne, Mark James
Metadata
Abstract
The research reported was inspired by the Perfect and Maylor (2000) chapter
‘Rejecting the Dull Hypothesis’. This suggested that cognitive ageing research should
not focus purely on whether younger adults outperform older adults on a given task.
Hartley, Speer, Jonides, Reuter-Lorez and Smith (2001) showed that older adults do
not maintain the dissociability of naming identity, visual identity, and spatial location
abilities that is seen in younger adults. Away from the ageing literature, Brown, Forbes
and McConnell (2006) demonstrated improvement in visual task performance when
the availability of verbal coding was increased. The hypothesis that older adults are
less likely to use task specific cognitive mechanisms during short-term visual memory
tasks was explored. This was carried out by means of a series of 8 experiments
(outlined below), which broadly looked at differences in verbal interference effects on
visual task performance, differences in Visual Patterns Task performance based on the
availability of verbal encoding, and assessed for age-related differences in interference
from an executive task in Visual Patterns Task performance. Data was interpreted
through the prism of the Scaffolding Theory of Aging (Park & Reuter-Lorenz, 2009),
which suggests that compensatory recruitment is employed both young and older
adults in response to extrinsic challenges such as task difficulty, and intrinsic
challenges, such as declining performance with age.
Experiments 1-3 focused on differential effects of articulatory suppression on visual
task performance between young (18-25) and older (60-75) adults. Older adults
showed negative effects of suppression in short-term maintenance tasks that were not
present in younger adults. Both age groups showed negative effects in a mental image
rotation task. This suggested a level of verbal activation in visual tasks for both age
groups, but that this activation was more common in older adults.
Experiments 4-5 assessed differences in Visual Patterns Task performance between
both age-groups depending on the availability of verbal encoding. Younger adults
displayed the benefit of available verbal encoding with simultaneous but not sequential
presentation of information. Older adults showed a benefit of verbal coding in the
simultaneous task if the sequential task featured ordered, not randomised presentation
pathways. This suggested that older adult task performance may be affected by all
conditions within an experiment, not just the current manipulation condition.
Experiments 6-7 demonstrated that older adults’ performance in the simultaneous
presentation version of the Visual Patterns Task is affected by the availability of verbal
encoding in the first task presented to them. Mean performance on subsequent
conditions was higher when ‘high verbal coding’ patterns were seen in the first
instance. This was not the case for younger adults. The demonstration of a benefit to
performance from the ‘high-verbal coding’ pattern set compared to the ‘low-verbal
coding’ set was a marker of higher overall performance across all task conditions for
younger adults, but not for the older group. This suggested that even if verbal
activation during visual task performance was an occurrence for older adults, it was
not necessarily a marker for improved performance.
Experiment 8 demonstrated that there were no age-related differences in the level of
interference from an executive task (Random Month Generation) on Visual Patterns
Task performance. This suggested that older adults do not try to actively recruit
executive processes during Visual Patterns Task performance to any greater extent
than younger adults do.
It is suggested that older adults do use specialised task mechanisms to a lesser extent
than younger adults in visual memory task performance. It is likely that this is a passive
outcome of a decreased inhibition of verbal coding mechanisms, rather than an active
attempt to maintain performance through the recruitment of executive cognitive
resources. This is seen by the lack of age-group effects from executive interference
tasks.