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E E Cooper

Publications and source records attributed to E E Cooper.

12 recordsLinked to original sources
PubMed1992

Unexceptional spatial memory in an exceptional memorist.

Rajan Mahadevan evidences an exceptional memory for arrays of digits. We tested whether Rajan's spatial memory was likewise exceptional. Eight control Ss and Rajan were instructed to remember the position and orientation of 48 images of common objects shown either to the left or the right of fixation and facing either left or right. Rajan's accuracy for judging whether the position and orientation of these pictures had changed when they were shown in a different sequence was lower than that of control Ss for both judgments. Rajan's exceptional memory capacity apparently does not extend to spatial relations.

Adult↗
PubMed1992

Metric invariance in object recognition: a review and further evidence.

Phenomenologically, human shape recognition appears to be invariant with changes of orientation in depth (up to parts occlusion), position in the visual field, and size. Recent versions of template theories (e.g., Ullman, 1989; Lowe, 1987) assume that these invariances are achieved through the application of transformations such as rotation, translation, and scaling of the image so that it can be matched metrically to a stored template. Presumably, such transformations would require time for their execution. We describe recent priming experiments in which the effects of a prior brief presentation of an image on its subsequent recognition are assessed. The results of these experiments indicate that the invariance is complete: The magnitude of visual priming (as distinct from name or basic level concept priming) is not affected by a change in position, size, orientation in depth, or the particular lines and vertices present in the image, as long as representations of the same components can be activated. An implemented seven layer neural network model (Hummel & Biederman, 1992) that captures these fundamental properties of human object recognition is described. Given a line drawing of an object, the model activates a viewpoint-invariant structural description of the object, specifying its parts and their interrelations. Visual priming is interpreted as a change in the connection weights for the activation of: a) cells, termed geon feature assemblies (GFAs), that conjoin the output of units that represent invariant, independent properties of a single geon and its relations (such as its type, aspect ratio, relations to other geons), or b) a change in the connection weights by which several GFAs activate a cell representing an object.

Adult↗
PubMed1991

Priming contour-deleted images: evidence for intermediate representations in visual object recognition.

The speed and accuracy of perceptual recognition of a briefly presented picture of an object is facilitated by its prior presentation. Picture priming tasks were used to assess whether the facilitation is a function of the repetition of: (a) the object's image features (viz., vertices and edges), (b) the object model (e.g., that it is a grand piano), or (c) a representation intermediate between (a) and (b) consisting of convex or singly concave components of the object, roughly corresponding to the object's parts. Subjects viewed pictures with half their contour removed by deleting either (a) every other image feature from each part, or (b) half the components. On a second (primed) block of trials, subjects saw: (a) the identical image that they viewed on the first block, (b) the complement which had the missing contours, or (c) a same name-different exemplar of the object class (e.g., a grand piano when an upright piano had been shown on the first block). With deletion of features, speed and accuracy of naming identical and complementary images were equivalent, indicating that none of the priming could be attributed to the features actually present in the image. Performance with both types of image enjoyed an advantage over that with the different exemplars, establishing that the priming was visual rather than verbal or conceptual. With deletion of the components, performance with identical images was much better than that with their complements. The latter were equivalent to the different exemplars, indicating that all the visual priming of an image of an object is through the activation of a representation of its components in specified relations. In terms of a recent neural net implementation of object recognition (Hummel & Biederman, in press), the results suggest that the locus of object priming may be at changes in the weight matrix for a geon assembly layer, where units have self-organized to represent combinations of convex or singly concave components (or geons) and their attributes (e.g., aspect ratio, orientation, and relations with other geons such as TOP-OF). The results of these experiments provide evidence for the psychological reality of intermediate representations in real-time visual object recognition.

Adult↗
PubMed1991

Object recognition and laterality: null effects.

In two experiments, normal subjects named briefly presented pictures of objects that were shown either to the left or to the right of fixation. The net effects attributable to hemifield were negligible: naming RTs were 12 msec lower for pictures shown in the left visual field but error rates were slightly lower, by 0.8%, for pictures shown in the right visual field. In both experiments, a second block of trials was run to assess whether hemifield effects would be revealed in object priming. Naming RTs to same name--different shaped exemplar pictures were significantly longer than RTs for identical pictures, thus establishing that a component of the priming was visual, rather than only verbal or conceptual, but hemifield effects on priming were absent. Allowing for the (unlikely) possibility that variables with large differential left-right hemifield effects may be balancing and cancelling each other out, we conclude that there are no differential hemifield effects in either object recognition or object priming.

Female↗
PubMed1991

Control of attention around the fovea.

Three experiments tested young adults' abilities to use size and location cues to find and identify a target letter in a visual field containing 8 to 12 letters. Location cues (relatively near to or far from the fovea) and size cues (relatively large or small) were given before the display. Compared with response times on neutral, no-cue trials, location and size cues produced independent cost and benefit effects. The best fitting quantitative models allow attentional resources to be distributed in ringlike areas varying in distance from the fixation point, within which further selection of items by their relative size is possible.

Adult↗
PubMed1991

Evidence for complete translational and reflectional invariance in visual object priming.

The magnitude of priming on naming reaction times and on the error rates, resulting from the perception of a briefly presented picture of an object approximately 7 min before the primed object, was found to be independent of whether the primed object was originally viewed in the same hemifield, left-right or upper-lower, or in the same left-right orientation. Performance for same-name, different-examplar images was worse than for identical images, indicating that not only was there priming from block one to block two, but that some of the priming was visual, rather than purely verbal or conceptual. These results provide evidence for complete translational and reflectional invariance in the representation of objects for purposes of visual recognition. Explicit recognition memory for position and orientation was above chance, suggesting that the representation of objects for recognition is independent of the representations of the location and left-right orientation of objects in space.

Adult↗
PubMed1990

The control of visual attention using multiple target features.

An experiment was conducted to determine how visual attention is allocated in response to pairwise combinations of location, color, and size cues. Subjects viewed displays of eight letters arranged into an 'X' pattern emanating from a central fixation point. The letters varied on the dimensions of location (foveal or parafoveal positions), size (large or small), and color (red or blue). Seven of the letters were 'X's and the remaining, critical letter was either an 'R' or an 'L'. Subjects were given advance cues about characteristics of the critical letter on two of the three dimensions (location size, and color). The cues varied in their validity such that on any trial either both dimensions were validly cued, one dimension was validly cued while the other was invalidly cued, or both cues were invalid. Subjects were instructed to try to use the cues to find the critical letter, and response times to identify it as an 'R' or an 'L' served as the main dependent measure. Two models were evaluated against the data; in one, location cues are viewed as having distinct effects on an early stage of attention whereas color and size cues operate only in a later, selection stage. In the other model, all cues are used in a similar way to select display items for serial, focal attention. In general, the serial processing model provides a more complete account of the data.

Adult↗
PubMed1975

Colestipol hydrochloride, a new hypolipidemic drug: a two-year study.

Colestipol hydrochloride is an insoluble, nonabsorbable copolymer with bile-acid-binding capacity. It prevents reabsorption of cholates from the intestinal tract into the enterohepatic circulation causing a net loss of bile acids, and therefore of cholesterol. Sixty subjects with cholesterol levels over 250 mg/100 ml were studied for 104 weeks. Patients with normal phenotypes, types 2,3, and 4, were given 5 gm three times daily and experienced an average drop of 40 mg/100 ml (14%). While patients with types 2,3, and 4 hyperlipidemia responded effectively, cholesterol levels in type 2 patients dropped earliest and most consistently with an average decrease of 58 mg/100 ml (19%). A comparable group of patients with hyperlipidemia taking placebo showed on average no change in serum cholesterol. Serum triglyceride values were not altered significantly. The resin is not absorbed from the gastrointestinal tract and produces a slight increase in fecal volume. Results of chemistries, enzyme assays, prothrombin times, hematology, and urinalysis and body weights wer unaltered. There was no evidence of lithogenic bile production. Colestipol is a tasteless and ordorless copolymer with high acceptability. Side effects were limited to occasional bloating, gas, and constipation. The drug is a safe, effective, palatable hypolipedmic agent.

Adult↗
PubMedDate not supplied

Cholesterol-lowering effect of colestipol hydrochloride given twice daily in hypercholesterolemic patients.

In a randomized design study in 66 hypercholesterolemic patients, dosages of 10 g of colestipol HCl twice daily lowered serum cholesterol an average of 19% more than placebo therapy. These results are comparable to those in other studies in which the same total daily dose was given in three or four doses. The most common side effect was constipation, reported by 6 patients on colestipol HCl and 3 patients on placebo. No untoward systemic reactions or abnormal laboratory data were seen except for a slight rise in serum alkaline phosphatase during colestipol HCl therapy. The drug was well accepted by most patients.

Adolescent↗