When Can Visual Images Be Re-Interpreted ? Non-Chronometric Tests of Pictorialism

The question of re-interpreting images can be seen as a new focus for the imagery debate since the possibility would appear to be a direct prediction of the pictorial account. Finke, Pinker and Farah (1989) have claimed that their results “refute” the earlier negative evidence of Chambers and Reisberg (1985), while Peterson, Kihlstrom, Rose & Glisky (1992) have used the ambiguous stimuli of Chambers and Reisberg to show that under certain conditions, these images may be reinterpreted after all. By employing newly devised tasks, our own experiments have provided further conflicting evidence concerning the conditions under which images can and cannot be reinterpreted. We consider their bearing on the fundamental ‘format’ issue which neither Finke et al (1989) nor Peterson et al. (1992) address directly. New Focus for Imagery Debate Kosslyn, Finke and other ‘pictorialists’ take internal representations to be importantly like external ones regarding their ‘privileged’ spatial properties of depicting and resembling their referents. Thus, Finke (1990) suggests that “perceptual interpretive processes are applied to mental images in much the same way that they are applied to actual physical objects. In this sense, imagined objects can be “interpreted” much like physical objects” (1990, p. 18). Elsewhere he suggests that “The image discoveries which then ‘emerge’ resemble the way perceptual discoveries can follow the active exploration and manipulation of physical objects” (1990, p. 171). The impasse in the imagery debate has led some (Anderson 1978) to conclude that the issue between pictorialism and the ‘tacit knowledge’ alternative is undecidable in principle on the basis of behavioral evidence. On the contrary, however, the experiments reported here show that divergent predictions from the contending theories may be readily formulated and tested with an appropriate experimental paradigm. At least part of the reason for the persistence of the imagery debate has been the fact that the dispute has centered upon alternative explanations of the same body of reaction-time data concerning tasks such as mental rotation and scanning. Since the rival theories make identical predictions for chronometric evidence, adducing new evidence of time-dependent measures, as has repeatedly been done, cannot strengthen the case for a pictorial, spatial medium against the tacit knowledge theory. Thus, experiments are needed on which the contending accounts deliver different predictions. The issue of reinterpreting visual patterns in mental imagery has recently emerged in this way as a new focus for the controversy since the question of whether, and under what conditions, novel information may be discovered from images provides a new means for testing the properties of the conjectured pictorial medium and the claimed parallel between imagery and perception. Our own evidence concerns perceptual organization tasks which provide unequivocal criteria of the successful rotation, inspection and reinterpretation of images using "recognition processes" and "shape classification" procedures. However, despite the demonstrated ease of our tasks under perceptual conditions, naive subjects have generally been unable to succeed in some of the tasks under imagery conditions as would be predicted on the pictorial theory. Just as in the classical “crucial experiment” of Michelson and Morley concerning the speed of light, one might conclude from our null results that the pictorial medium, like the luminiferous ether, does not exist. However, as is familiar from the history of science, the situation is somewhat more complicated, as our own further experiments and those of others have shown. There can be strictly no such thing as a “crucial experiment”, since a falsified prediction can always be blamed on the auxiliary hypotheses on which any theory must depend. Thus, with the shift to nonchronometric investigations of image reinterpretation, the situation in the “imagery debate” has become less a matter of deciding between predictively equivalent theories than a matter of comparing their respective virtues according to the usual criteria of explanatory comprehensiveness, simplicity etc. in relation to the full set of available evidence. Above all, rather than being posed on either side of the debate in a partisan manner as “refuting” the competing theory, the inconsistent data on image reconstrual provide an opportunity for considering the significance of experimental conditions. A step in this direction has been taken by Peterson, Kihlstrom, Rose and Glisky (1992), who have used the ambiguous duck/rabbit figure to show that, under certain conditions, images may be reinterpreted after all, despite the null results of Chambers and Reisberg (1985).