Effect of preacquisition UCS exposure on classical conditioning of the rabbit's nictitating membrane response

Conditioning of the rabbit nictitating membrane response was found to be inversely related to the number (0, 50, 200, 350) and intensity, (0, 1, 3, 5 mA) of preacquisition UCS exposures and directly related to the interval between preexposure and acquisition (0 or 24 hr). The results were discussed in terms of sensory adaptation, habituation, blocking, and emotional reactivity.     

The role of CS-US contiguity in classical conditioning of the rabbit's nictitating membrane response to serial stimuli

The rabbit's nictitating membrane response was classically conditioned to a serial tone-light compound (CS1-CS2), in which the CS1-CS2 and CS2-US intervals were each manipulated over the values of 200, 400, 800, and 1600 msec in a between-groups, factorial design. In addition, at each level of the CS2-US interval, there was a control group that received CS2 and the US. Within the serial compound, the CS2 was found to be highly efficacious in that the CS2-US interval determined the rate of CR acquisition to the compound as a whole and to CS2 in particular. Moreover, CR probability during CS2 largely overlapped the performance of the corresponding single-stimulus controls. Outside the context of the compound, CR frequency on CS2 test trials fell below control levels at the 200- and 400-msec CS2-US intervals. The results can be interpreted as indicating that a generalization decrement or information loss occurred in transferring from compound training to CS2 testing. In addition, the theories of Rescorla and Wagner (In A. Black & W. F. Prokasy, Eds., Classical conditioning II, New York: Appleton-Century-Crofts, 1972) and Mackintosh (Psychological Review, 1975, 82, 276–298) may be extended to account for the present results.     

Blocking acquisition of the rabbit's nictitating membrane response to serial conditioned stimuli

Three experiments demonstrated that prior training with one stimulus (CS1) would block acquisition of the rabbit's nictitating membrane response (NMR) to another stimulus (CS2) which was more contiguous to the US during serial compound training (CS1-CS2-US). Specifically, the CS1-US interval was 800 msec, which produces only a modest rate of CR acquisition, while the CS2-US interval was 400 msec, which is an optimal value for the NMR preparation. Experiment 1 demonstrated blocking when CS1 overlapped CS2, and Experiment 3 demonstrated blocking when CS1 and CS2 were presented in a strictly sequential fashion. Experiment 2 showed that the magnitude of blocking in the serial compound was comparable to that obtained in a simultaneous compound in which both the CS1-US and CS2-US intervals were 800 msec, thus making CS2 less contiguous with the US than in the serial compound. Moreover, the level of responding to CS2 in all serial compound groups (blocking and control) was lower than in the simultaneous compound groups. The present findings provide further evidence that the associative consequences of CS-US contiguity can be highly attenuated by processes of attention or competition for associative strength.     

The US preexposure phenomenon in the conditioned suppression paradigm: A role for conditioned situational stimuli

Four experiments evaluated possible associative and nonassociative accounts of the retardation in the acquisition of conditioned suppression produced by repeated prior exposure to an electric shock US. Associative interference resulting from conditioning of situational stimuli during preexposure to shock was suggested by the findings that signaling the occurrence of high-intensity shock with a discrete nontarget CS during the preexposure phase reduced the magnitude of the retardation effect compared to an unsignaled shock preexposure treatment (Experiments 1 and 4), nonreinforced presentations of putatively conditioned situational stimuli prior to conditioned suppression training reduced the magnitude of the retardation effect (Experiment 2), and the magnitude of the retardation effect was directly related to the intensity of preexposure shock (Experiment 3). Nonassociative interference was suggested by the finding that signaling the occurrence of low-intensity shock with a discrete nontarget CS during the preexposure phase did not reduce the magnitude of the retardation effect compared to an unsignaled shock preexposure treatment (Experiment 4). It was suggested that associative and nonassociative mechanisms govern the US preexposure phenomenon obtained in the conditioned suppression paradigm, and their relative contribution depends upon the intensity of shock.     

The effects of retention interval on preschool children's short-term memory of verbal items

The short-term recall of word-triads was tested, comparing retention over three types of intervals within 24 preschoolers. Retention was significantly lower in the 16 sec unfilled interval condition than in the immediate test condition. This result, predicted from preschoolers' rehearsal deficiency, differs from those obtained in previous adult and child studies. A filled interval condition, requiring irrelevant verbal activity during the 16 sec period, significantly reduced recall from that of the unfilled interval condition. Recognition of the word items on a subsequent recognition test was greater than chance and was not affected by interval condition. This suggests that the condition effects in short-term recall did not disrupt the long-term storage of the items.     

The CS-US interval function in rabbit nictitating membrane response conditioning: Single vs multiple trials per conditioning session

The effect of varying trials per day conditions on the CS-US interval or interstimulus interval (ISI) function in rabbit nictitating membrane response conditioning was studied in two experiments. Experiment 1 showed that a 1250-msec ISI was more effective than a 250-msec ISI when there was 1 trial/day. Experiment 2 showed that as the number of trials per day decreased from 20 to 1, the superiority of the 250-msec ISI group over the 1250-msec ISI group declined, with a reversal at 1 trial/day. Results are interpreted in terms of the role of a hypothesized CS-elicited short-duration orienting response in CR performance.     

Preconditioning exposure to the unconditined stimulus affects the acquisition of a conditioned emotional response

Four experiments examined the UCS preexposure phenomenon using conditioned suppression of food-reinforced responding as a measure of excitatory conditioning, and electric shock as a UCS. In Experiment 1, groups of rats were preexposed to unsignaled 0.8-mA electric shocks for 0, 1, 3, 5, or 10 days, and then conditioned with a 0.8-mA electric shock. Preexposure to electric shock 1 day prior to conditioning enhanced the acquisition of a CER, whereas preexposure to electric shock for 3, 5, or 10 days prior to conditioning attenuated the acquisition of a CER as a direct function of the number of days of preexposure. In Experiments 2 and 2A, groups of rats were preexposed to unsignaled electric shocks of 0.3, 0.5, 0.8, or 1.3 mA for 10 days, and then conditioned with a 0.8-mA electric shocl. All groups preexposed to electric shock acquired the CER at a slower rate than a group not preexposed to electric shock. The greatest attenuation of CER conditioning occurred when the same intensity electric shock was used during both the preexposure and conditioning phases. In Experiment 3, groups of rats were preexposed to signaled electric shocks of either 0.5, 0.8, or 1.3 mA, and then conditioned with a 0.8-mA electric shock. All groups preexposed to electric shock acquired the CER at a slower rate than a group not preexposed to electric shock. As in Experiments 2 and 2A, the greatest attenuation of CER conditioning occurred when the same intensity electric shock was used during both the preexposure and conditioning phases. In Experiment 4, groups of rats were preexposed to series of 0.5, 0.8, or 1.3-mA electric shocks which they could escape by performing a chain-pull response. Rats in each of these groups had yoked partners which received the same number, intensity, and temporal pattern of electric shocks, but could not perform a response to escape shock. All groups were then conditioned with a 0.8-mA electric shock. Rats preexposed to escapable electric shocks showed equal or greater attenuation of CER conditioning than rats which could not escape shock during the preexposure phase. These results are discussed in terms of nonassociative and associative explanations of the UCS preexposure phenomenon.     

Classical conditioning and retention of the infant's eyelid response: effects of age and interstimulus interval

Independent groups of 10-,20-, and 30-day-old infants were subjected to a classical eyelid conditioning procedure involving either a 500- or a 1500-msec interstimulus interval (ISI). Ten days later, all received a second conditioning session. A reliable increase in conditioned responding was observed at all ages but only by infants receiving the 1500-msec ISI. Although age was not a significant factor in any conditioning measure except final performance level, which was greater for the oldest than for the youngest group, it did influence long-term retention. A reliable memory component was observed in the Session 2 performance of infants initially trained at 20 and 30 days but not at 10 days. These data demonstrate the importance of temporal parameters in the formation of conditioned associations very early in infancy and provide evidence for the long-term behavioral consequences of those associations.     

The infant's acquisition of knowledge of bimodally specified events

Four-month-old infants viewed, for a duration of several minutes, two objects that bounced in synchrony with two percussion sounds. This synchrony was the only information tying each sound to its respective object. During the viewing the infants learned about the relationships between sound and object. Learning was revealed in two ways. In a search test, infants looked for an object when its sound was played. In a transfer test, infants' declining interest in a sound presented alone generalized to the visible object that the sound specified. Studies that reversed the spatial locations of the objects revealed that sound-object learning, rather than place or response learning, guided infants' perceptual exploration.     

The effects of stimulus type,training, and chronological age on children's identification and recoding of multidimensional stimuli

Kindergarten and second-grade children (75 and 99 months of age, respectively) were first taught that the two stimuli within each of four pairs of multidimentional stimuli differed with respect to their values on every one of three bivalued dimensions: color, size, and form. Each of the eight stimuli was then presented twice, one at a time, and the child was asked either to find its duplicate (eight encoding trials) or to find its complementary mate (eight recoding trials) among the complete set of eight stimuli. Next, each of the eight stimulus compounds was presented twice as a display stimulus for 5 sec and, after a delay of 10 to 15 sec, the child was asked to find the display stimulus (eight trials of encoding plus memory) or its complement (eight trials of recoding plus memory) among the complete set. The stimuli for half the children in each age group were standard unitary compounds (e.g., a large red circle, a small blue square, etc.) and for the other half they were partitioned stimuli with their dimensional values spatially separated (e.g., large arrow, circle outline, and patch of color). Half of the children in each of these subgroups were given a basic pretraining, and the other half received extended pretraining, in recoding the stimulus attributes. The results indicated that unitary stimuli were easier to encode but the partitioned stimuli were easier to recode, that recoding was much more difficult than encoding, that extended training improved recoding performance, and that second graders were slightly better at encoding and much better at recoding than the kindergarten children. The patterns of performance on the tasks involving memory were similar to those just described. The results were discussed in terms of children's abilities to analyze multidimensional stimuli into their dimensional components.     

The Home Observation for Measurement of the Environment: A comment on Elardo and Bradley's review

The published and unpublished research pertaining to Caldwell's Home Observation for Measurement of the Environment (HOME) inventory was recently reviewed by R. Elardo and R. H. Bradley (Developmental Review, 1981, 1, 113–145). Their review was unfortunately deficient in a number of respects. For example, certain methodological issues bearing on the interpretation of the available data were either unrecognized or dismissed without adequate consideration. In addition, some of the data in the studies cited which contradicted or clouded their conclusions were omitted. An extension and reanalysis of the conclusions reached by Elardo and Bradley in light of recently published studies which were not included in their review, and data not discussed in the studies which were reviewed, is provided. Methodological problems are highlighted, and directions for future research are suggested.     

Human covariation judgment: Accuracy and strategy

Judgment strategy is proposed as a contributor to the variability of findings in past research on human covariation judgment. Mathematically sophisticated judgment strategies will accurately judge all event covariations. However, faulty judgment rules will also produce correct judgments of many event relationships. Several methods have been used in past research to identify subjects' strategies of covariation judgment. Each of these methods indicates that humans employ simplistic, error-prone rules to judge event relationships. Shifts in covariation strategy use are proposed as a source of past findings that judgment accuracy depends on the decision conditions.     

The influence of introversion/extraversion on the skin conductance response to stress and stimulus intensity

A series of studies compared skin conductance level (SCL) for introverts and extraverts during a series of tones varying in both stimulus intensity (SI) and the amount of stress preceding the tones. When a difficult paired-associate task preceded the tones, both groups were about the same for 83 dB tones but extraverts were much higher at 103 dB, introverts failing to show an increase as a function of SI. There were no differences between the two groups following a simple paired-associate task, both groups showing a similar increase with increased SI. Finally, SCL was higher for introverts than extraverts during tones preceded by a rest period, and this was especially true for the early trials and for lower SI (75 and 83 dB compared with 100 and 103 dB). Taken together, these results suggest that SCL is higher for extraverts at higher levels of arousal but that the reverse is true for lower levels of arousal. This relationship is consistent with the theory that introverts have a “weak nervous system” which develops transmarginal or protective inhibition under stress.     

Dogmatism, field dependence, and perception of demand characteristics in a verbal operant conditioning experiment

Using a 2 × 2 analysis of variance design, effects of dogmatism and field dependence on subjects' awareness of demand characteristics in a verbal operant conditioning experiment were investigated. From 103 introductory psychology students who participated in a replication of an earlier verbal conditioning experiment, 92 were randomly selected for final study. It was found that only subjects aware of the purpose of the conditioning study appeared to “condition”. Subject awareness was assessed by a series of converging questions which were independently content analyzed by two judges and coded to yield a total awareness score. Based on earlier research it was expected that dogmatism and field dependence would interact to affect levels of awareness. The two-way interaction was statistically significant (p < .05) as predicted. The results were discussed in terms of speculations regarding the modes of perceptual functioning involved in perceiving demand cues.     

Bounded rationality and cognitive development: Upper limits on growth?

Piaget's characterization of formal operational thought and human judgment psychologists' model of bounded rationality are considered as two conflicting models dealing with the same domain of interest: the nature and limits of mature thought. Piaget's suggestion that the formal operational thinker brings the skills of hypothetico-deductive logic to deal adequately with environmental complexity is in sharp contrast with judgment psychologists' evidence that information-processing limitations and faulty reasoning leave decision makers poorly equipped to deal with their decision environments. While the two approaches have generated conflicting models, a look at the respective data bases demonstrates their complementarity. Considered together, the literatures in formal operations and bounded rationality make a formidable contribution to understanding the capacities and limits of mature cognition.     

Development: Compared to what?: Contrast effects in age-comparative paradigms

Recent controversies about judgment competence of preschool and adolescent children are considered as being a possible product of contrast effects. That is, perceived abilities of children of a given age group may depend on the ages of the other subjects in the experiment. An experiment was done to test the possibility of contrast effects in age-comparative experiments. One group of subjects read about three experimental tasks in which 6-year-old children performed better than 4-year-olds. A second group read about 6-year-olds performing worse than 8-year-olds on the same tasks. Performance levels of 6-year-olds were the same on the two forms. For each task subjects rated the competence of each of the two age groups on the task and predicted the performance of the two groups on a related task. Undergraduate subjects' competence ratings and predictions were higher for 6-year-olds when compared to 4-year-olds than when compared to 8-year-olds. Psychology graduate students showed the same contrast effect for predictions but not for competence ratings. The results are discussed in terms of potential biases in age-comparative methods in developmental psychology.     

Olfactory dysfunction in man: anatomical and behavioral aspects

We reviewed studies examining the olfaction of patients with brain damage for the purpose of discerning correlations between disordered structure and function. Patient samples included those with neurological disorders and neurosurgical interventions and recording of spontaneous or elicited neuronal activity. Brain areas involved in olfaction include the olfactory bulbs, the orbitofrontal and medial temporal cortices, the thalamus, and the amygdala. Despite recent advances in olfactory anatomy, understanding of how these structures are related to olfactory detection, discrimination, and recognition continues to be limited. Inadequate localization of brain lesions and lack of comprehensive behavioral assessment have thus far prevented a detailed account of the organization of olfaction in the human brain.     

Effective list length and part-whole transfer in first-graders' multitrial free recall

First-gradens' multitrial free recall shows an effective list-length (ELL) effect: an initial recall gain followed by a constant output level that fluctuates in item content. The part-whole transfer paradigm was used to investigate ELL. The ELL effect occurred in whole-list learning regardless of whether the prior task consisted of relevant practice, irrelevant practice, or an unrelated task. Relevant part-list learning resulted in positive transfer which declined from a high to a marginal level over the course of whole-list learning. Other analyses indicated a general deficit in the use of strategies. A response-strength model was used to explain the ELL effect and the transfer results.