Paula Engelbrecht & Itiel Dror

1. The effect of manipulating image decomposability on mental rotation performance in older and younger adults. Paula Engelbrecht & Itiel Dror

2. Introduction • A variety of cognitive functions have been found to decline with age: • Memory (e.g. Park et al., 1996) • Reasoning (e.g. Gilinsky & Jud, 1994) • Spatial-visualisation ability (e.g. Salthouse et al., 1990) • Underlying assumption: Younger and older adults use the same processing mechanisms.

3. Introduction • Does this assumption hold true? • Neuroimaging study: • No age-related difference in memory for visual scenes. • Age-related prefrontal overactivation and underactivation in the medial temporal lobe (Gutchess et al., 2005). • Strategic processes can compensate for age-related functional decline. • Qualitative age-related differences in the way in which information is processed.

4. Introduction • Qualitative age-related differences have also been found in mental imagery. • Mental rotation paradigm (Dror et al., 2005): • Younger adults employ a piecemeal strategy. • Older adults employ a holistic strategy. • Aim: To investigate the boundary conditions of these age-related differences. • Are they fixed and inflexible?

5. Introduction • Image decomposability was manipulated through the use of colour. • High decomposability: Image segments were highlighted with colour. • Low decomposability: line-drawings. • Rationale: High decomposability manipulation facilitates piecemeal processing.

6. Predictions • Differences in rotation slope reflect qualitative differences in the underlying mental rotation process (e.g. Folk & Luce, 1987; Dror et al., 2007). • If image decomposability affects mental rotation then this should be reflected in differing rotation slopes for high and low decomposability images. • Otherwise rotated at the same rate.

7. Method • Participants • 20 older adults (12 females) with a mean age of 76 years (SD = 5.2 years). • 20 younger adults (15 females) with a mean age of 26 years (SD = 3.4 years).

8. Method

9. Method

10. Results • Response time data was analysed separately for younger and older adults using ANOVAs. • Stimulus decomposability (high and low) and angle of rotation (0, 35, 70 and 105 degrees) were the two within subjects variables.

11. Results

12. Results • The younger adults responded faster to high decomp. (M = 1485.19 ms, SE = 125.49 ms) than to low decomp. (M = 1551.04 ms, SE = 123.84 ms) stimuli. • No significant difference for the older adults. • Main effect reflects initial encoding not mental rotation performance.

13. Results

14. Discussion • Younger adults: • Differences in rotation slopes for high and low decomposability images suggests that these are processed differently. • Previous research associates shallow rotation slopes with holistic processing and steep rotation slopes with piecemeal processing.

15. Discussion • Older adults: • Rotation performance did not vary as a function of stimulus decomposability. • Suggests that they employed the same processing strategy to rotate both high and low decomposability stimuli. • A previous study found that older adults prefer a holistic processing strategy (Dror et al., 2005). • Holistic processing is less resource intensive (Logan, 1988).

16. Conclusions • Findings suggest that older adults favour a holistic processing style regardless of image decomposability. • Their processing strategies appear to be less affected by environmental manipulations. • Investigating qualitative changes deepens our understanding of the aging mind.

17. Angle Overall Younger Adult Older Adults 0 21.18% (SE = 1.5%) 21.89% (SE = 2.1%) 20.5% (SE = 2.12%) 35 22.29% (SE = 1.6%) 23.3% (SE= 2.3%) 21.3% (SE = 2.3%) 70 24.89% (SE = 1.6%) 27% (SE = 2.2%) 22.8% (SE = 2.2%) 105 24.71% (SE = 1.9%) 26% (SE = 2.6%) 23.4% (SE = 2.6%) Results