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Biomedical subjects

S Pinker

Publications and source records attributed to S Pinker.

51 records · Page 3Linked to original sources
PubMed1991

Cholinesterase inhibition in the scopolamine model of dementia.

Scopolamine produces a satisfactory model of the attentional and secondary memory deficits seen in Alzheimer's disease (AD) that can be used to screen compounds for potential therapeutic usefulness. Physostigmine, which is known to enhance memory in AD, produced marked and widespread antagonism of the scopolamine-induced impairments, indicating the sensitivity of the model and establishing its relevance for the clinical situation. HP 029, a novel anticholinesterase, also exhibited widespread potency in the model, and in an international trial with patients with AD, it subsequently showed improvement on similar measures, demonstrating the predictive use of the scopolamine model.

Alzheimer Disease↗
PubMed1983

Directional scanning of remembered visual patterns.

We report a set of experiments that helps to define the conditions under which mental image scanning may be used spontaneously for specific, practical purposes. Subjects were shown a dot pattern, followed by an arrow, and their task was to say whether the arrow was pointing at any of the previously seen dots. When no advance information was provided about the arrow's location, reaction time for correctly verifying that an arrow was pointing at a dot increased linearly with increasing arrow-dot distance, and the subjects almost always reported scanning a mental image in order to make their judgments. However, when a cue for the arrow's location was presented 2 sec beforehand, reaction time was uncorrelated with distance, and most of the subjects reported using an alternative strategy based on the determination in advance of correct directions from that location to the dots. When given only 1 sec of advance information about arrow location, most subjects reported using a combined image-scanning and advanced determination strategy, resulting in a reaction time function that increased only for the farthest distances. Because in each of these experiments instructions to form or to scan mental images were never given, these findings address the most common criticisms of the image-scanning paradigm.

Form Perception↗
PubMed1982

Spontaneous imagery scanning in mental extrapolation.

We report an experiment that suggests a functional application of mental-image scanning. After subjects inspected a simple dot pattern, the pattern was removed, and they were then shown an arrow at an unexpected location. Their task was to judge as quickly as possible whether the arrow pointed at any of the dots in the previously observed pattern. Although the subjects were never instructed to form or scan mental images, most of them reported having done so in order to make their judgments, and their reaction times were directly proportional to the distances separating the dots and the arrows, as typically found in image-scanning experiments. Imagery scanning may therefore serve a useful function when one must judge spatial relations between the positions of remembered objects and newly specified locations.

Discrimination Learning↗
PubMed1980

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.

Adult↗
PubMed1980

Mental imagery and the third dimension.

What sort of medium underlies imagery for three-dimensional scenes? In the present investigation, the time subjects took to scan between objects in a mental image was used to infer the sorts of geometric information that images preserve. Subjects studied an open box in which five objects were suspended, and learned to imagine this display with their eyes closed. In the first experiment, subjects scanned by tracking an imaginary point moving in a straight line between the imagined objects. Scanning times increased linearly with increasing distance between objects in three dimensions. Therefore metric 3-D information must be preserved in images, and images cannot simply be 2-D "snapshots." In a second experiment, subjects scanned across the image by "sighting" objects through an imaginary rifle sight. Here scanning times were found to increase linearly with the two-dimensional separations between objects as they appeared from the original viewing angle. Therefore metric 2-D distance information in the original perspective view must be preserved in images, and images cannot simply be 3-D "scale-models" that are assessed from any and all directions at once. In a third experiment, subjects mentally rotated the display 90 degrees and scanned between objects as they appeared in this new perspective view by tracking an imaginary rifle signt, as before. Scanning times increased linearly with the two-dimensional separations between objects as they would appear from the new relative viewing perspective. Therefore images can display metric 2-D distance information in a perspective view never actually experiences, so mental images cannot simply be "snapshot plus scale model" pairs. These results can be explained by a model in which the three-dimensional structure of objects is encoded in long-term memory in 3-D object-centered coordinate systems. When these objects are imagined, this information is then mapped onto a single 2-D "surface display" in which the perspective properties specific to a given viewing angle can be depicted. In a set of perceptual control experiments, subjects scanned a visible display by (a) simply moving their eyes from one object to another, (b) sweeping an imaginary rifle sight over the display, or (c) tracking an imaginary point moving from one object to another. Eye-movement times varied linearly with 2-D interobject distance, as did time to scan with an imaginary rifle sight; time to tract a point varied independently with the 3-D and 2-D interobject distances. These results are compared with the analogous image scanning results to argue that imagery and perception share some representational structures but that mental image scanning is a process distinct from eye movements or eye-movement commands.

Cues↗