Mental extrapolation in patterns constructed from memory

Finke and Pinker (1982, 1983) showed subjects an array of dots followed by an arrow in a blank field, and asked them to determine whether the arrow pointed to any of the previously seen dots. Response times were linearly related to the distance between the arrow and the nearest dot, suggesting that subjects spontaneously used an internal scanning or extrapolation process to perform the task. We replicate and extend this finding by varying the retention interval, and by employing a paradigm in which subjects’ eyes are closed and the arrows are described to them using a coordinate scheme. We also show that subjects are unable to predict the form of the data when the task simply is described to them. Results suggest that mental scanning along a straight path can be performed on images reconstructed from memory, and that it does not depend on the ongoing perception of a continuous surface, on physical eye movements, or on demand characteristics.     

The quantitative measure of pattern representation in images using orientation-specific color aftereffects

A quantitative method is developed for assessing the quality of pattern information in imagery, using the magnitude of color aftereffects as an objective index. Subjects were given instructions to project imagined bar patterns of particular width and orientation onto adapting color fields, in such a manner as to simulate standard conditions for establishing the McCollough effect. Our control procedures indicate that the resulting orientation-specific complementary color aftereffects cannot be attributed to the conditioning of particular directions of eye scanning movements to color processing during adaptation, or to other possible sources of experimental bias. Furthermore, subjects who rated themselves prior to the adaptation procedure as having relatively vivid imagery showed significantly larger aftereffects than those who reported having relatively low imagery. These results not only provide an important confirmation of our earlier finding that imagination can replace physical pattern information in the formation of basic color-feature associations in the human visual system, but also demonstrate that these aftereffects can provide a practical measure of the fidelity of pattern representation in visual images.     

Emergent two-dimensional patterns in images rotated in depth

Once a person has observed a three-dimensional scene, how accurately can he or she then imagine the appearance of that scene from different viewing angles? In a series of experiments addressed to this question, subjects formed mental images of a set of objects hanging in a clear cylinder and mentally rotated their images as they physically rotated the cylinder by various amounts. They were asked to perform four tasks, each demanding the ability to "see" the two-dimensional patterns that should emerge in their images if the images depicted the new perspective view accurately--(a) Subjects described the two-dimensional geometric shape that the imagined objects formed in an image rotated 90 degrees; (b) they "scanned" horizontally from one imagined object to another in a rotated image; (c) they physically rotated the empty cylinder together with their image until two of the imagined objects were vertically aligned; and (d) they adjusted a marker to line up with a single object in a rotated image. The experimental results converged to suggest that subjects' images accurately displayed the two-dimensional patterns emerging from a rotation in depth. However, the amount by which they rotated their image differed systematically from the amount specified by the experimenter. Results are discussed in the context of a model of the mental representation of physical space that incorporates two types of structures, one representing the three-dimensional layout of a scene, and the other representing the two-dimensional perspective view of the scene from a given vantage point.     

Making AI meaningful again

Synthese - Artificial intelligence (AI) research enjoyed an initial period of enthusiasm in the 1970s and 80s, but this enthusiasm was tempered by a long interlude of frustration when genuinely...     

Disentangling the adult attention-deficit hyperactivity disorder endophenotype: parametric measurement of attention

Attention deficit hyperactivity disorder (ADHD) persists frequently into adulthood. The decomposition of endophenotypes by means of experimental neuro-cognitive assessment has the potential to improve diagnostic assessment, evaluation of treatment response, and disentanglement of genetic and environmental influences. We assessed four parameters of attentional capacity and selectivity derived from simple psychophysical tasks (verbal report of briefly presented letter displays) and based on a "theory of visual attention." These parameters are mathematically independent, quantitative measures, and previous studies have shown that they are highly sensitive for subtle attention deficits. Potential reductions of attentional capacity, that is, of perceptual processing speed and working memory storage capacity, were assessed with a whole report paradigm. Furthermore, possible pathologies of attentional selectivity, that is, selection of task-relevant information and bias in the spatial distribution of attention, were measured with a partial report paradigm. A group of 30 unmedicated adult ADHD patients and a group of 30 demographically matched healthy controls were tested. ADHD patients showed significant reductions of working memory storage capacity of a moderate to large effect size. Perceptual processing speed, task-based, and spatial selection were unaffected. The results imply a working memory deficit as an important source of behavioral impairments. The theory of visual attention parameter working memory storage capacity might constitute a quantifiable and testable endophenotype of ADHD.     

Mental extrapolation and cognitive penetrability: reply to Ranney and proposals for evaluative criteria

We propose three criteria for establishing that mentally extrapolated motions are impenetrable with respect to one's knowledge, beliefs, or expectations about the nature of corresponding physical motions, and we review recent findings on mental extrapolation and representational momentum that appear to meet these criteria. We also respond to some arguments recently proposed by Ranney (1989) and Hubbard and Bharucha (1988) that representational momentum is cognitively penetrable. We conclude that mental extrapolations are governed to at least some extent by the inherent properties of the underlying internal mechanisms.     

Explorations of creative visual synthesis in mental imagery

The mental synthesis of visual patterns has been previously studied by instructing subjects to imagine assembling the component parts in specific ways. We report two experiments that show that subjects can often discover recognizable patterns in imagery when the component parts are randomly chosen and are provided without instructions for how they might be assembled. On each trial, the subjects were given a set of three parts, consisting of geometric forms, lines, or alphanumeric characters, and were instructed to close their eyes and imagine combining the parts to make some type of recognizable pattern. They were successful in doing so on about 40 % of the trials. Many of these mentally synthesized patterns were strikingly creative, and few of them could be predicted, either by the experimenter or by the subjects themselves, simply by knowing what the parts were. On the contrary, most of the subjects reported that they had performed the task by imagining various combinations of the parts until a recognizable pattern “emerged.” These findings show that visual discoveries in imagery can be reliably induced under appropriate laboratory conditions.     

Memory confusions for real and imagined completions of symmetrical visual patterns

In Experiment 1, subject ratings indicated that it was easier to imaginally complete half of a symmetrical form when the form was symmetrical about the vertical axis than when the form was rotated so that it was symmetrical about the horizontal axis. In Experiment 2, new subjects saw these same forms, some presented as wholes and some presented as halves. Compared with controls, subjects who were instructed to imagine the vertically symmetrical half forms as complete had more difficulty remembering which forms had been presented as wholes and which had been presented as halves. Imagery and control groups did not differ in ability to discriminate half from whole horizontally symmetrical forms. The results are consistent with predictions from Johnson and Raye’s (1981) reality monitoring model that discriminating memories of imagined and perceived events should be a function of the amount of cognitive operations included in the memory.     

Area and contrast effects upon perceptual and imagery acuity

We measured the size of visual fields within which actual and imagined circular patterns could be resolved, as the patterns varied in both area and relative contrast. As pattern area increased, imagery fields increased in size at the same rate as perceptual fields. However, as the relative contrast between parts of the patterns was reduced, perceptual fields diminished in size, while imagery fields did not. for all variations of pattern area and contrast, fields in imagery were roughly the same shape as fields in perception. A control experiment provided no support for the possible criticism that these results might be explained on the basis of subjects' expectations for the size and shape of the imagery fields, especially since control subjects falsely believed that reductions in contrast would reduce considerably the size of these fields. Although these findings suggest that images and physical objects are functionally equivalent at pattern-processing levels of the visual system, they demonstrate that images and objects are not functionally equivalent at certain levels of the visual system where information about relative contrast is processed.