Evidence for criterion shifts in visual perceptual learning: data and implications.

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. Although the increase in false alarm rates suggests a strategic shift in response criteria for detection, we demonstrate that there are multiple potential explanations, including explanations that do not require strategic shifts on the part of the observer. The empirical evidence and analysis of alternative explanations reinforce the inference that visual perceptual learning may involve more than changes in perceptual sensitivity and that cortical circuits beyond the primary visual areas may be involved.

Evidence for the role of self-priming in epistemic action: expertise and the effective use of memory.

Epistemic actions are physical actions people take to simplify internal problem solving rather than to move closer to an external goal. When playing the video game Tetris, for instance, experts routinely rotate falling shapes more than is strictly needed to place the shapes. Maglio and Kirsh [Kirsh, D., & Maglio, P. (1994). On distinguishing epistemic from pragmatic action. Cognitive Science, 18, 513-549; Maglio, P. P. (1995). The computational basis of interactive skill. PhD thesis, University of California, San Diego] proposed that such actions might serve the purpose of priming memory by external means, reducing the need for internal computation (e.g., mental rotation), and resulting in performance improvements that exceed the cost of taking additional actions. The present study tests this priming hypothesis in a set of four experiments. The first three explored precisely the conditions under which priming produces benefits. Results showed that presentation of multiple orientations of a shape led to faster responses than did presentation of a single orientation, and that this effect depended on the interval between preview and test. The fourth explored whether the benefit of seeing shapes in multiple orientations outweighs the cost of taking the extra actions to rotate shapes physically. Benefits were measured using a novel statistical method for mapping reaction-time data onto an estimate of the increase in processing capacity afforded by seeing multiple orientations. Cost was measured using an empirical estimate of time needed to take action in Tetris. Results showed that indeed the increase in internal processing capacity obtained from seeing shapes in multiple orientations outweighed the time to take extra actions.

An investigation of perceptual and decisional influences on the perception of hierarchical forms.

When observers are asked to identify the global and local dimensions of hierarchical forms, their responses are typically faster when the dimensions are consistent rather than inconsistent. This effect, which we refer to as the dimensional consistency effect, has been demonstrated numerous times in paradigms requiring responses to a single dimension. However, most hypotheses regarding dimensional consistency effects address the simultaneous perception of both dimensions, and the manner in which the information about these dimensions may (or may not) 'interact'. Most explanations of the dimensional consistency effect attribute the effect to perceptual influences. The present study uses the constructs of general recognition theory (Ashby and Townsend, 1986 Psychological Review 93 154-179) to represent the source of the effect in terms of both perceptual and decisional influences. In addition, a complete identification response paradigm was used to collect data on the simultaneous perception of both global and local dimensions of hierarchical forms. Analyses of multidimensional signal detection measures and fits of parametric models of the perceptual space were used to guide inferences, with all sources of evidence pointing to both perceptual and decisional influences.