Kenta nakajima¹, Takehiro Nagai; ¹Institute of Science Tokyo

It remains unclear whether there are any differences in the stages of visual processing underlying impressions of different material attributes, such as glossiness or aesthetics. This study investigated how “temporal attitude”, the participants’ expectation of stimulus duration, modulates the neural dynamics of material perception, thereby revealing the underlying processing stages. Participants viewed 320 object images and rated either glossiness or aesthetics in separate blocks. Temporal attitude was manipulated between blocks by varying the proportion of short (100-ms) and long (1000-ms) trials. Each block consisted of either long trials only, or a mixture of long and short trials presented in equal proportion. EEG was recorded while participants performed the task, and decoding analyses based on linear support vector machine were conducted using sliding time windows on the raw EEG signals. The decoding results indicated qualitatively different patterns across attributes and temporal-attitude conditions. For glossiness, decoding accuracy tended to be higher when short presentations were mixed and participants expected shorter presentation durations. For aesthetics, decoding accuracy tended to be higher when only long presentations were included and participants expected longer viewing durations. A statistically significant interaction between attribute and temporal attitude was observed in the 200–300 ms time window, indicating differential impacts of temporal attitude on glossiness-related and aesthetics-related EEG signals. Overall, these findings suggest that implicit expectations about viewing duration alter the temporal dynamics of neural representations in attribute-specific ways. While the effects are modest, the present approach can be a useful framework for investigating temporal aspects of neural processing for different material impressions.

Acknowledgements: This work was supported by JST SPRING, Japan Grant Number JPMJSP2180 to Kenta Nakajima.