Fifty-five late Dutch-English bilinguals were tested on their ability to perceive a difficult L2 speech contrast (the English /æ/-/ε/ contrast) in three different tasks: A categorization task, a word identification task and a lexical decision task.
To better illustrate the phase-independent property of perceived contrast in binocular contrast combination, we re-plotted the average perceived contrast of the four observers as functions of the phase-shift between the two monocular test gratings (Figure 3A).
The average (across base contrast levels, phase shifts between monocular images, and subjects) normalized perceived contrast, defined as the contrast of the matched probe grating divided by the base contrast of each condition, is plotted in Figure 3B as a function of interocular contrast ratio between the monocular images.
It takes a strong eye to perceive shadows and contrast.
The sixth (the "covered eye") objection contrasts not perceiving an object (in one sensory modality) with not knowing it.
The perceived contrast of a central sinusoidal grating patch (4 c/deg stationary grating, or 2 c/deg drifting at 2 deg/sec, 40% contrast) was measured in the presence and absence of a 95% contrast annular grating (same orientation, spatial frequency, and drift rate).
For this study, we chose a sub-set of experimental conditions that elicit a substantial shift in perceived contrast in normal observers (approximately a 20 40% reduction of apparent contrast), and measured the magnitude of contrast-contrast surround suppression for both a stationary and a drifting grating version of the stimulus.
The most common versions of the task involve measuring the perceived contrast of a patch of sinusoidal grating in the presence of an annular surround [33], [34], [35], [36], [37].
Before the new book came out, people would occasionally ask when she intended to get back to "real writing" - "as if writing a movie isn't something!" she snorts - but there is a perceived contrast between the bite of her prose and the slightly more indulgent tone of her movies that fans of the former resent.
We find that both upward and downward luminance steps attenuate the perceived contrast of a simultaneously presented target, the upward step somewhat more than the downward step.
The presence of the surround resulted in the perceived contrast being 68% of actual contrast for the control group, and 53% of actual contrast for the migraine group (t(44) = 2.86, p<0.01; data shown in Figure 4D).
