How Prior Expectations Influence Older Adults' Perception and Action During Object Interaction.

Area of Science:

• Human Perception and Action
• Lifespan Psychology
• Motor Control

Background:

• The size-weight illusion demonstrates how perceived object size influences weight perception.
• Understanding how this illusion impacts behavior across the lifespan is crucial for explaining age-related changes in motor control.
• Previous research has not fully explored the influence of size cues on predictive motor actions in older adults.

Purpose of the Study:

• To investigate the influence of visual size cues on the size-weight illusion in older adults.
• To examine how size cues affect the predictive application of fingertip forces during object lifting in older adults.
• To compare the perception and action responses of older adults to those of younger adults.

Main Methods:

• Participants (older and younger adults) experienced the size-weight illusion by lifting objects of varying sizes but constant weight.
• Fingertip forces applied during grip and lift were measured to assess predictive motor control.
• Perceptions of object heaviness were recorded.

Main Results:

• Older adults exhibited a robust size-weight illusion, comparable to younger adults.
• Both age groups accurately perceived real weight differences.
• Unlike younger adults, older adults showed no modulation of grip force or lifting strategy based on object size cues.

Conclusions:

• Older adults' perception of weight is influenced by object size, similar to younger adults.
• A dissociation exists between perceptual and action-based responses to size cues in older adults.
• Impaired predictive control in action, rather than altered perception, may contribute to age-related difficulties in manual object interaction.