PubMed Health⌕ Search

Biomedical subjects

C D Heth

Publications and source records attributed to C D Heth.

10 recordsLinked to original sources
PubMed1994

Place recognition and way finding by children and adults.

Children and adults were escorted on their first walk across our university campus and were periodically led off the original route during the return trip. During the return, we stopped prior to intersections on and off the original route to obtain estimates of place recognition accuracy and confidence. The subjects were then asked to point to the path that led back to the start and were corrected if wrong. Accuracy of place recognition was intermediate in a way-finding task requiring reversal of an incidentally learned novel route. However, accuracy increased as subjects were farther from the original route, indicating that the presence of novel landmarks boosted the discrimination of old and new places. Eight-year-old children were less accurate than 12-year-old children and 25-year-old adults, who did not differ in accuracy. There was a similar age difference in the ability to point to the direction to return when subjects correctly recognized that they were off route. The results are used to develop a model of way finding by place recognition.

Adult↗
PubMed1992

Levels of aggregation and the generalized matching law.

Concurrent operant behavior is often described using molar response tendencies measured over many sessions. In contrast, other models relate the allocation of behavior to momentary or molecular processes that operate over shorter periods. In this article, a formal model of the statistical properties of molecular behavioral matching is developed. Molar matching is the result when many individual bouts of responding are aggregated. However, behavioral allocation at the molecular level will differ from the molar result. The model indicates that aggregation effects should be controlled in analyses of matching and that the comparison of molecular theories of concurrent operant behavior with molecular models of matching performance affords ideographic analyses of choice behavior.

Animals↗
PubMed1989

The effect of logarithmic transformation on estimating the parameters of the generalized matching law.

The generalized matching law was initially stated as a nonlinear relation between reinforcement-rate ratios and response-rate ratios. Often, the variables of the law are transformed logarithmically to remove the nonlinearity; empirical results are then fit to the model through least-squares regression. However, the logarithmic expression of the matching law is a biased statistical representation of the law itself. In particular, the logarithmic transformation alters the quantitative conclusions to be drawn from a least-squares regression analysis. A Monte Carlo study of the effect of transforming matching-law data demonstrated that (a) the estimates of one or both of the parameters of the generalized matching law are biased, (b) the measure of goodness of fit (R(2)) is inaccurate, and (c) predictions generated by the fitted parameters are incorrect. Alternative approaches to logarithmic transformations are shown to alleviate these problems.

Journal Article↗
PubMed1983

Spatial cognition: gathering strategies used by preschool children.

How preschool children retrieve hidden objects was examined in two cross-sectional studies. The first was a simple task in which 1- and 3-year-olds saw two treats hidden in their living room. The newly walking infants generally sought the closer treat first, providing evidence for a least-distance spatial strategy. However, this strategy was affected by a tendency to approach the hiding place most recently baited. Three-year-old children used a least-distance strategy regardless of the order of hidings. In Experiment 2, 3- and 5-year-olds saw 12 puzzle pieces hidden in various containers equally spaced within a naturally furnished children's laboratory. Factors in addition to age were the distinctiveness of the containers and a requirement to return to the center of the array after each retrieval. Overall, children of both age groups were quite successful at this task, retrieving 11 of the pieces. However, 3-year-olds were less efficient, retrieving fewer pieces and requiring more searches. Detailed analyses of errors and patterns of choices indicated differential processes in achieving their performance. Three-year-old children showed the use of memories for events, discrimination of classes of hiding places, and efficient spatial biases. Five-year-old children were more likely to exhibit these processes concurrently.

Child Behavior↗
PubMed1979

Response versus place learning by human infants.

Two cross-setional studies examined how infants learn the location of visual events. In Experiment 1, infants of 4, 8, and 12 mo of age learned to turn one way to view a novel pattern. In a subsequent transfer task, they were rotated to face the opposite side of the room. The 4-mo-old infants tended to err by repeating their previously learned response, but within 16-20 trials their performance was comparable to the higher levels maintained by the older infants. These results suggest that young infants learn the location of the pattern primarily in terms of response cues, whereas older infants employ both response cues and place cues. Experiment 2 was designed to independently assess the use of response cues and place cues by infants of 4, 8, 12, and 16 mo of age. All infants were able to rapidly learn and remember the location of the novel pattern when they were given response cues. There was a gradual emergence of place-cue use associated with age. It is suggested that the decrease in infant egocentricity in such spatial localization tasks may in fact reflect an age-related increase in the variety of reliable cues responded to by infants.

Cues↗
PubMed1976

Simultaneous and backward fear conditioning as a function of number of CS-UCS pairings.

Four experiments examined the possibility that the outcome of simultaneous and backward fear conditioning procedures might depend upon the number of CS-UCS pairings. A punishment procedure will rats as subjects and shock as the UCS was used; the amount of suppression produced by response-contingent CS presentations indexed the strength of acquired fear. Experiments 1, 3, and 4 examined the suppressive tendencies of simultaneous-and backward-trained CSs after 0, 10, 20, 40, 80, and 160 pairings. The pattern of data suggested that initial pairings have the effect of increasing suppressive tendencies of the CS, while subsequent pairings decrease them. In addition, evidence of fear inhibition was found after 160 pairings in the case of the backward paradigm. Experiment 2 examined several nonassociative accounts based upon differential shock exposure. Groups given 10 pairings or 80 pairings were compared to ggroups given 10 pairings plus 70 shock-alone presentations. The results indicated that number of pairings, rather than number of UCS occurrences, is the important factor in decreasing the initial suppression. The evidence for eventual inhibition in the backward paradigm suggests that this occurs through the acquisition of inhibitory tendencies which are antagonistic to the previously conditioned excitation.

Animals↗
PubMed1975

Reinstatement of fear to an extinguished conditioned stimulus.

Four experiments are reported which demonstrate the ability of an unconditioned stimulus (UCS) presentation following extinction to partially reinstate the conditioned response. These experiments are interpreted in terms of the strengthening of an extinction-reduced UCS representation. The first two experiments address alternative interpretations in terms of sensitization, reinstating the stimulus conditions of acquisition, conditioning of background cues, and stimulus generalization. Experiment 3 suggests that reinstatement is possible with a UCS qualitatively different from that used in conditioning. Experiment 4 explores an alternative extinction procedure which especially preserves the conditioned stimulus-unconditioned stimulus association while encouraging modification of the UCS representation. The results are discussed both in terms of related empirical phenomena, such as spontaneous recovery and sensory preconditioning, and in relation to the general role of the UCS representation in conditioning.

Acoustic Stimulation↗
PubMedDate not supplied

Conditioned taste aversion induced by wheel running is not due to novelty of the wheel.

Under a within-subjects design, food- and water-restricted rats showed a significant reduction in consumption of a flavor associated with the opportunity to run compared to another flavor associated with a novel wheel without the opportunity to run. Furthermore, there was no evidence that consumption of the flavor paired with the novel wheel differed from a home cage control.

Animals↗