Abstract
Purpose:
It has been shown that normal aging reduces the ability to remember an object’s visual features such as its colour and shape when presented for short durations. We examined the effects of aging on visual short term memory (VSTM) for complex visual tasks that require participants to remember both the object and its spatial location (object-location binding).
Methods:
Two experiments were conducted: object recall and location identification. Seventeen young (mean age =23.3 years), and 17 normally ageing subjects (mean age=66.5 years) participated. In experiment 1, the ‘memory display’ comprised two or four Snodgrass stimuli (memory loads ML2 and ML4 respectively). These were presented sequentially, for 650ms, at random locations on a screen followed by a 1000ms blank interval, and then the presentation of a ‘test display’. The test display used a spatial marker to cue one of the previously shown stimuli locations. Participants were asked to report which target had been shown at that particular spatial location. In experiment 2, the memory display was similar to experiment 1, but in the test display one of the previously displayed objects was shown as a test target. All the possible spatial locations were also displayed, each identified by a numbered marker. Participants were asked to report the spatial location at which the target object had been shown in the memory display.
Results:
The percentage correct responses were analysed using 2 × 2 mixed ANOVA. Older subjects showed a significantly lower performance compared to younger subjects (Experiment 1: F(1,32)=27.41, p<0.001; Experiment 2: F(1,32)=13.49, p=0.001). Posthoc analysis showed that, in the first experiment (object recall), older participants showed a significantly (p<0.01) lower performance of 10% and 24% with ML2 and ML4 respectively, compared to younger subjects. In experiment 2 (location identification), older subjects’ performance decreased significantly (p<0.05) by 4% and 17% for ML2 and ML4 respectively, compared to younger subjects.
Conclusions:
Older subjects have reduced VSTM capacity for tasks that require object-location binding. This is apparent even with relatively small memory loads.
Keywords: 413 aging •
591 memory