Eye movements in reading and information processing.

It is generally accepted that there is something special about reasoning by using mental images. The question of how it is spe- cial, however, has never been satisfactorily spelled out, despite more than thirty years of research in the post-behaviorist tradition. This article considers some of the general motivation for the assumption that entertaining mental images involves inspecting a picture-like object. It sets out a distinction between phenomena attributable to the nature of mind to what is called the cognitive architecture, and ones that are attributable to tacit knowledge used to simulate what would happen in a visual situation. With this distinction in mind, the paper then considers in detail the widely held assumption that in some important sense images are spatially displayed or are depictive, and that examining images uses the same mechanisms that are deployed in visual perception. I argue that the assumption of the spatial or depictive nature of images is only explanatory if taken literally, as a claim about how images are physically instantiated in the brain, and that the literal view fails for a number of empirical reasons - for example, because of the cognitive penetrability of the phenomena cited in its favor. Similarly, while it is arguably the case that imagery and vision involve some of the same mechanisms, this tells us very little about the nature of mental imagery and does not support claims about the pictorial nature of mental images. Finally, I consider whether recent neuroscience evidence clarifies the debate over the nature of mental images. I claim that when such questions as whether images are depictive or spatial are formulated more clearly, the evidence does not provide support for the picture-theory over a symbol- structure theory of mental imagery. Even if all the empirical claims were true, they do not warrant the conclusion that many people have drawn from them: that mental images are depictive or are displayed in some (possibly cortical) space. Such a conclusion is incompatible with what is known about how images function in thought. We are then left with the provisional counterintuitive conclusion that the available evidence does not support rejection of what I call the "null hypothesis"; namely, that reasoning with mental images involves the same form of representation and the same processes as that of reasoning in general, except that the content or subject matter of thoughts experienced as images includes information about how things would look.

/pdf/mental-imagery-in-search-of-a-theory-401jk114di.pdf

Mental imagery: in search of a theory.

https://science.sciencemag.org/content/sci/181/4102/810.full.pdf

Miniature Eye Movement

Visual illusion and action

The length of initial voluntary saccades to a target were measured in three experiments. It was found that saccade length varied as a function of the number, locus and distance of non-target stimuli present in the visual field. Eye movements tended to be directed toward the “center of gravity” of the stimuli close to the target. These systematic changes seem to be independent of task requirements for acuity. Some implications are discussed.

Effect of Non-Target Stimuli upon Length of Voluntary Saccades:

Two experiments are reported in which a decrement in the magnitude of the Muller-Lyer illusion was found if free eye movements were allowed. Little or no decrement was obtained if Ss fixated one point of the figure during inspection. In one experiment eye movements were recorded. Saccades across the perceptually short side of the Muller-Lyer figure were found to be shorter than across the perceptually long side. After inspection with free eye movements, the saccades became more nearly equal on the two sides. Such changes in eye movements did not occur if Ss fixated one point during the inspection period. The data are interpreted in terms of perception being determined by the efferent readiness activated by visual input. According to this interpretation, the decrement in the magnitude of the illusion results from recalibration of the efferent programs.

Charles W. White

Papers

Eye movements and decrement in the Muller-Lyer illusion.