Asymmetric Transfer of Perceptual Learning of Luminance- and Contrast-Defined Motion

Abstract:

Perceptual learning was used as a tool for studying motion perception. The pattern of transfer of learning of luminance- (LM) and contrast-modulated (CM) motion is diagnostic of how their respective processing pathways are integrated. Twenty observers practiced fine direction discrimination with either additive (LM) or multiplicative (CM) mixtures of a dynamic noise carrier and a radially isotropic texture modulator. The temporal frequency was 10 Hz, speed was 10 deg/s, and duration was 400 ms, with feedback. Group 1 pre-tested CM for 2 blocks, trained LM for 16 blocks, and post-tested CM for 6 blocks during 6 sessions on separate days. In Group 2, the LM and CM roles were reversed. The d' improved almost twofold in both groups. There seemed to be full transfer from CM to LM but no significant transfer from LM to CM. The pattern of post-switch improvement was asymmetric as well—no further learning during the LM post-test versus rapid relearning during the CM post-test. These strong asymmetries suggest a dual-pathway architecture with Fourier channels sensitive only to LM signals and non-Fourier channels sensitive to both LM and CM. We hypothesize that the channels tuned for the same motion direction but different carriers are integrated using a MAX operation.

Keywords: perceptual learning, second-order motion, dual-pathway theory, form-cue invariance

Preprint (pdf) Matlab reports (html) Perceptual Learning Project

Matlab Reports

In the process of analyzing the data, developing the models, and fitting them to the data, we wrote various Matlab scripts. These scripts generated HTML reports via Matlab's "publish" feature. The most important reports are made available here. Use the Back button in your browser to return to this page.

• MLZ02_dpr_group_fits.html -- The definitive script. All data figures in the published article are based on it.
• MLZ02_dpr_group_fits-summary.txt -- All you need to know about Table 1 in the published article (and then some more)
• MLZ02_plot_dprime.html -- Older script with preliminary analyses.