The effect of short-term training on repetition probability effects for non-face objects

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neuroimaging

Background:

• Repetition suppression (RS) magnitude in fMRI is influenced by stimulus repetition probability (P(rep)).
• Previous research suggests the P(rep) effect relies on long-term stimulus experience.
• The impact of short-term learning on RS and P(rep) modulation is not well understood.

Purpose of the Study:

• To investigate how short-term perceptual learning (PL) affects repetition suppression (RS) and its modulation by repetition probability (P(rep)).
• To examine these effects in both familiar object categories (cars) and unfamiliar faces.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure RS and P(rep) effects.
• Participants underwent a 10-day perceptual learning (PL) period for specific stimuli.
• Measurements were taken before and after the PL period for cars and unfamiliar faces.

Main Results:

• A significant P(rep) effect was observed for both faces (in FFA) and cars (in LO) before training.
• Perceptual learning improved subordinate categorization of trained stimuli.
• Post-training, RS magnitude remained unchanged, but the P(rep) effect disappeared for both stimulus types.

Conclusions:

• Short-term perceptual learning experience can modulate predictive processes, as evidenced by the absence of the P(rep) effect after training.
• This suggests that predictive coding mechanisms are sensitive to recent learning experiences, not solely long-term familiarity.