The following is a summary of “Varying test-pattern duration to explore the dynamics of contrast-comparison and contrast-normalization processes,” published in the January 2023 issue of Ophthalmology by Graham, et al.

For a study, researchers looked at the dynamics of contrast-comparison and contrast-normalization processes. 

Observers were exposed to a grid of Gabor patches at one contrast for one second, followed by a test pattern that lasted between 12 and 3,012 milliseconds before the adapt pattern was presented again (1 second). In every adapt pattern, there was a 50% contrast in every Gabor patch. The test pattern and adapt pattern were identical, but the test pattern’s Gabor patches featured two distinct contrasts that changed from row to row (horizontal test pattern) or column to column (vertical test pattern). Finding the direction of the contrast variation in the test pattern was the job (in other words, the observer performed a second-order orientation identification task). Each test pattern had two contrasts that were altered while maintaining a fixed difference between the two contrasts. 

They had previously discovered that when the test period was around 100 ms, the observer’s performance was poor for test patterns that comprised contrasts above and below the contrast of the adapt patterns (what they dubbed the “straddle effect”). They discovered that the straddling effect endured throughout all of the test durations they employed. The length of the exam had a significant impact on other aspects of the results. They discovered that a straightforward model with contrast comparison and contrast-normalization procedures adequately explained the psychophysical findings. 

The findings shed some light on these processes’ behavior.

Reference: jov.arvojournals.org/article.aspx?articleid=2785307