Current literature maintains that success or failure in the performance of an action can modify perception of the objects of that action. The tests of that modification, however, may have measured memory rather than perception. To address this issue, the current experiment had observers throw a marble into various sized holes and assess their size through either a haptic or verbal measure. They respond either before the throw while the hole is visible (control condition), after the throw while the hole is visible (perception condition), or after the throw while the hole is not visible (memory condition). It was found that observers judged the hole size to be different depending on their throwing success only during the memory condition. This casts doubt on the conclusion of an action-specific perception account (Witt, 2011), and instead we propose an action-specific memory account.

We investigated the physiological mechanism of grapheme-color synesthesia using metacontrast masking. A metacontrast target is rendered invisible by a mask that is delayed by about 60 ms; the target and mask do not overlap in space or time. Little masking occurs, however, if the target and mask are simultaneous. This effect must be cortical, because it can be obtained dichoptically. To compare the data for synesthetes and controls, we developed a metacontrast design in which nonsynesthete controls showed weaker dichromatic masking (i.e., the target and mask were in different colors) than monochromatic masking. We accomplished this with an equiluminant target, mask, and background for each observer. If synesthetic color affected metacontrast, synesthetes should show monochromatic masking more similar to the weak dichromatic masking among controls, because synesthetes could add their synesthetic color to the monochromatic condition. The targetmask pairs used for each synesthete were graphemes that elicited strong synesthetic colors. We found stronger monochromatic than dichromatic U-shaped metacontrast for both synesthetes and controls, with optimal masking at an asynchrony of 66 ms. The difference in performance between the monochromatic and dichromatic conditions in the synesthetes indicates that synesthesia occurs at a later processing stage than does metacontrast masking.Keywords Visual perception . Visual awareness . Neural mechanisms . Metacontrast . Synesthesia After more than a century of being on the fringes of perceptual science (Galton, 1880), synesthesia has seen renewed interest in the past few years with the application of modern psychophysical methods (Cytowic, 2002;Ramachandran & Hubbard, 2001a, 2001b. Synesthesia is both involuntary and stable (Brang & Ramachandran, 2011;Cytowic & Eagleman, 2009); as a perception in one modality that occurs as a result of stimulation in another, it represents a failure of accurate perception of the properties of the world. In this way, synesthesia is a tool for uncovering perceptual mechanisms, which are often investigated by exploring the limits of perceptual capability. Investigating when and how perception breaks down (e.g., measuring thresholds) often informs researchers about the mechanisms of perception. The natural breakdown of correspondence between physical stimulation and perception can thus be informative about perceptual mechanisms.We can begin to locate the level of grapheme-color synesthesia in the brain by examining the point of perceptual breakdown using direct psychophysical methods. The best-documented type of synesthesia is grapheme-color synesthesia, in which letters and numbers evoke an idiosyncratic experience of color for each grapheme. In this study, we employed a metacontrast-masking paradigm to compare the performance of grapheme-color synesthetes and nonsynesthete control participants using both dichromatic and monochromatic stimuli. If both synesthetes and controls experienced stronger masking under monochromatic than under dic...

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