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Poster Session B: Wednesday, August 13, 1:00 – 4:00 pm, de Brug & E‑Hall

Temporal Processing of Spatial Frequencies in Visual Word, Object, and Place Recognition

Clémence Bertrand Pilon¹, Gabriela Milanova, Anjali Singh, Martin Arguin; ¹Université de Montréal

Presenter: Clémence Bertrand Pilon

The temporal dynamics of spatial frequency (SF) processing in visual recognition were studied through three studies involving word (Exp.1), object (Exp.2) and place (Exp.3) recognition tasks in normal adult observers. They had to report the target stimulus presented in a 200 ms display using a four-alternative-forced-choice task (4AFC). The stimuli were made of an additive combination of the signal (target stimuli) and of a visual white noise patch wherein the signal-to-noise ratio (SNR) varied randomly across stimulus duration. Four SF conditions were defined with center frequencies of 1.2, 2.4, 4.8 and 9.6 cycles per degree. Contrary to the "coarse-to-fine" theory (Bar, 2003), the results indicated a more complex, non-sequential processing pattern which varies across stimulus classes. In Exp.1 (words), the highest SF range dominates early processing, with a shift toward lower SFs later on. In Exp.2 (objects), initial processing was dominated by the 4.8 cpd band, followed briefly by 9.6 cpd, then 1.2 cpd, and finally 2.4 cpd. In Exp.3 (places), processing was dominated first by the 2.4 cpd band, followed by 9.6 cpd and 4.8 cpd bands. These findings challenge the coarse-to-fine model. Also, all studies found that SF processing is modulated not only by the passage of time but also by the oscillatory frequency spectrum of the stimulus, indicating that visual recognition involves an intricate interaction of temporal and SF factors.

Topic Area: Visual Processing & Computational Vision

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