Henry A. Cross

Short-term haptic memory for complex objects

College students actively felt complex objects for 3 sec, and, after delay intervals of 5, 15, 30, or 45 sec, they received either the same object or a different object for comparison. In a signal detection framework, it was observed that d′ scores were significantly higher for the 5- and 15-sec intervals than for the 30- and 45-sec intervals. Although a clearly negatively accelerated function was not obtained, this is one of the rare instances in which any decay function has been observed for haptic memory. Although it seems counterintuitive that the entire short-term-memory decay function occupies the narrow band extending from 15 to 30 sec, it is clear from previous studies that short-term haptic memory is unique. Results were discussed in terms of findings in both active- and passive-touch experiments.

The effects of tetraethyl lead on behavior in the rat

Abstract The behavioral effects on rats of various doses of tetraethyl lead, administered intragastrically, were measured on the following: bar press responding for food, two-choice discrimination under negative reinforcement, and emotional responses in the open field. Bar press response rates were drastically curtailed following administration of high doses of lead. Both trials to criterion and mean latency to criterion were detrimentally affected by administration of single doses of lead prior to acquisition of the discrimination. Lead had similar effects on these same measures in reversal of the original discrimination and in retention of the reversal. The performance deficits were not attributable to the tetraethyl radical; control injections of tetraethyl silane were without effect on all behavioral measures in the discrimination task. In addition, the results did not appear to be a function of emotional factors as lead did not influence trials to avoidance criterion or open field behavior. It was concluded that lead given intragastrically can impair learning and memory in the rat.

Perceived numerosity as a function of array number, speed of array development, and density of array items

College-student subjects engaged in judgments of numerosity received stimulus arrays on a computer screen that varied in their number level (low, medium, and high), the speed with which the array developed (slow, medium, or fast), and the density of the items in the array (low or high density). The subjects overestimated number when the array was small (75-125 items) but significantly underestimated number when it was at a medium (150-250) or high level (550-650). Density of array items was a significant variable, since subjects showed more underestimation under the high-density condition. Additionally, there was a speed × density interaction. The results are discussed with respect to which class of variable, sensory or cognitive, most influences perceived numerosity.

The LD50 value of tetraethyl lead

Im Hinblick auf den offensichtlichen Mangel eines LD50-Wertes für Bleitetraethyl wurde bei intragastrischer Applikation im Rattenversuch der Wert 14,18 mg/kg (Spielraum 12,62–15,93) ermittelt.

The effects of constrained rehearsal on judgments of temporal order

Tzeng and Cotton’s (1980) study-phase retrieval model holds that temporal encoding of words is acquired through the establishment of contextual associations among list items. Such associations are strengthened by a subject’s ability to rehearse previous items, that is, to engage in displaced rehearsals. Since displaced rehearsals are critical in the study-phase model, to place constraints on such rehearsals should alter performance for the memory of temporal order. Five different rehearsal strategies were employed within a distractor paradigm to test this prediction. Two distinct instructional sets were also administered, with one half of the subjects instructed that serial order information was important, while the remaining subjects were told only that a free recall test would be given. Differences were found for serial position scores among the different rehearsal strategies in support of the study-phase retrieval model. Informed and uninformed instructional groups did not differ in temporal memory.

Assessment of visual recall and recognition learning in a museum environment

Subjects were tested for visual learning of objects in a small museum immediately following either total or limited exposure to the museum environment. Both recall and recognition memory results were better in the limited than in the total exposure condition. Attention time to exhibits correlated positively with recall but showed no relationships with the recognition measure. Findings were discussed in relation to early field research on museum visitor attention patterns.

Extinction in a straight alley as a function of varied quality and quantity of reward sequence

Six groups of albino rats were extinguished in a straight alley after receiving two daily trials an one of the following varied quality and/or quantity of reward sequences: 1 regular pellet followed by 1 regular pellet, 1 regular pellet followed by 1 sucrose pellet, 1 sucrose pellet followed by 1 regular pellet, 1 regular pellet followed by 16 sucrose pellets, 1 sucrose pellet followed by 16 sucrose pellets, and 16 sucrose pellets followed by 1 sucrose pellet. Further evidence for an extension of the sequential hypothesis to include quality of reward was provided by showing that greater resistance to extinction results when a high-quality reward follows a low-quality reward than when the opposite sequence occurs. In addition, variations in both quantity and quality of reward produced more resistance to extinction than variations in quantity of reward alone.

SHORT-TERM HAPTIC MEMORY FOR THREE-DIMENSIONAL OBJECTS

In 8 experiments college students felt 32 geometric objects and were tested in a signal-detection framework to same or distractor items. Retention intervals and intervening experiences were also manipulated following initial touching. In all instances performance was high, and there was no evidence of a decline in haptic sensitivity over the retention intervals employed. These surprising results were interpreted as consistent with the 1985 contention of Klatzky, Lederman, and Metzger that the haptic modality constitutes an expert system.

Extinction as a function of varied quality and quantity of reward sequence in a straight alley

Four groups of male albino rats were extinguished in a straight alley after receiving two daily trials on one of the following varied quality and/or quantity of reward sequences: 1 alfalfa pellet followed by 1 sucrose pellet, 1 sucrose pellet followed by 1 alfalfa pellet, a single alfalfa pellet followed by 16 sucrose pellets, and a single sucrose pellet followed by 16 sucrose pellets. The results indicated that a high-quality reward following a low-quality reward produced greater resistance to extinction than when a low-quality reward followed a high-quality reward. The findings were interpreted within Capaldi’s sequential theory.

Determination of a DL using two-point tactual stimuli: A signal-detection approach

Following a suggestion by Underwood, a difference limen was determined for two-point tactual stimuli, all of which were supraliminal. A signal-detection (TSD) procedure was employed, and consideration was given to subsequent research possibilities in this area.