Perceptual learning in contrast detection: presence and cost of shifts in response criteria

Abstract

Contemporary theoretical accounts of perceptual learning typically assume that observers are either unbiased or stably biased across the course of learning. However, standard methods for estimating thresholds, as they are typically used, do not allow this assumption to be tested. We present an approach that allows for this test specific to perceptual learning for contrast detection. We show that reliable decreases in detection thresholds and increases in hit rates are not uniformly accompanied by reliable increases in sensitivity (d ), but are regularly accompanied by reliable liberal shifts in response criteria (c). In addition, we estimate the extent to which sensitivity could have increased in the absence of these liberal shifts. The results pose a challenge to the assumption that perceptual learning has limited or no impact on response criteria.

Evidence for criterion shifts in visual perceptual learning: Data and implications

“…That work documented that reliable reductions in detection and discrimination thresholds were accompanied by false alarm rates that either did not decrease or reliably increased. These findings were replicated and extended (Wenger & Rasche, 2006) using evidence is sufficient for detection but not for identifying the stimulus as being in state A. Let b be the observer's bias for judging the stimulus to be present, given that the perceptual evidence is not sufficient for detection.…”

“…This evidence, along with data suggesting that perceptual practice can produce reliable liberal shifts in detection responses (Seitz, Nanez, Holloway, Koyama, & Watanabe, 2005;Wenger & Rasche, 2006;Wild & Busey, 2004), motivates the two central hypotheses of the present effort, which we tested in the context of perceptual learning for the detection of grayscale contrast. The first hypothesis is that practice can lead to appreciable liberal shifts in response bias for detection without any concomitant changes in response bias for identification.…”

“…The latter could suggest important roles for selective attention, memory, or other influences, such as might be available by way of back-projections within the visual system (e.g., Di Lollo, Enns, & Rensink, 2000;Lamme & Roelfsema, 2000;Li, Piëch, & Gilbert, 2004;Ling & Carrasco, 2006;Sigman & Gilbert, 2000;Sigman et al, 2005). However, if the experimental approach does not provide the data necessary to measure both types of potential changes, or if it does not adequately control for the possible effects of different types of response bias, any inferences regarding any single basis for change is potentially suspect.In a large number of the studies on perceptual learning, an experimental approach-an adaptive version of a Work on visual perceptual learning for contrast detection has shown that reliable decreases in detection thresholds are accompanied by reliable increases in false alarm rates (Wenger & Rasche, 2006). The present study assesses the robustness and replicability of these changes, demonstrating that they are independent of a variety of task demands (i.e., the specific method used for perceptual practice and threshold estimation) and the presence or absence of trial-by-trial feedback and that the source of the increases can be found in shifts in changes in sensitivity and in bias for detection, identification, or both.…”

“…In a large number of the studies on perceptual learning, an experimental approach-an adaptive version of a Work on visual perceptual learning for contrast detection has shown that reliable decreases in detection thresholds are accompanied by reliable increases in false alarm rates (Wenger & Rasche, 2006). The present study assesses the robustness and replicability of these changes, demonstrating that they are independent of a variety of task demands (i.e., the specific method used for perceptual practice and threshold estimation) and the presence or absence of trial-by-trial feedback and that the source of the increases can be found in shifts in changes in sensitivity and in bias for detection, identification, or both.…”

Cognitive science and the law

“…Bias shifts could underlie performance changes, and recent work by Wenger [35,36] suggests that changes in bias might not result from what are traditionally thought of as cognitive processes, but might reside closer to the perceptual processing and might not be under strategic control.…”