Exposure to inescapable shock produces both activity and associative deficits in the rat

Interference with shuttle-box escape learning following exposure to inescapable shock is often difficult to obtain in rats. The first experiment investigated the role of shock intensity during escape training in the apparent fragility of the effect. Experiment 1A demonstrated that the magnitude of the interference effect was systematically related to shock intensity during shuttle-box testing. At .6 mA, a robust effect was obtained, whereas at .8 mA and 1.0, little or no deficit in the escape performance of inescapably shocked rats was observed. Experiment 1B demonstrated that the deficit observed in Experiment 1A depended upon whether or not rats could control shock offset. Experiment 2 suggested that preshock may suppress activity and that higher shock levels may overcome this deficit. Experiment 3 tested this as the sole cause of the escape deficit by requiring an escape response which exceeded the level of activity readily elicited by a 1.0-mA shock in both restrained and preshocked rats. In such a task, preshocked rats performed more poorly than did restrained controls. These results are consistent with the possibility that inescapable shock may, in addition to reducing activity, produce an associative deficit. Experiment 4 more clearly demonstrated that inescapable shock produces deficits in performance which cannot be expleined by activity deficits and which appear to be associative in nature. It was shown that inescapable shock interfered with the acquisition of signaled punishment suppression but not CER suppression. The theoretical implications of these data for explanations of the manner in which prior exposure to inescapable shock interferes with escape learning were discussed.     

Immunization of opioid analgesia: Effects of prior escapable shock on subsequent shock-induced and morphine-induced antinociception

In Experiment 1, it was shown that experience with escapable foot shock 4 hr prior to a session of 80 inescapable tail shocks prevented the occurrence of an analgesic response normally observed immediately following the tail shock. It has been suggested by J. W. Grau, R. L. Hyson, S. F. Maier, J. Madden, and J. D. Barchas (Science, 1981, 213, 1409–1411) that the analgesia that occurs following this number of inescapable tail shocks is mediated by endogenous opioid systems. To further explore the influence of escapable shock on opiate-mediated analgesia, Experiment 2 examined the effects of prior escapable shock on the long-term analgesia reaction that occurs upon brief exposure to shock 20 hr after morphine administration. Rats were given escapable shock, inescapable shock, or no shock 4 hr prior to a morphine injection. Twenty hours following the injection, all subjects received 5 brief foot shocks and were then immediately given tail-flick analgesia tests. Subjects which received inescapable shock or no shock prior to the morphine injection displayed a significant analgesic response. However, subjects which received escapable shock prior to morphine were not analgesic following brief exposure to shock. Thus, escapable shock seems to directly influence the activation of opioid analgesia systems.     

Prior exposure to inescapable electric shock in rats affects extinction behavior after the successful acquisition of an escape response

In Expt 1, rats exposed to 64 inescapable electric shocks in a restrainer or merely restrained were later given either 0, 5, 15 or 30 escape/avoidance training trials with a two-way shuttlebox procedure that does not lead to interference with escape acquisition due to prior exposure to inescapable shock. After escape training all rats were given an escape/avoidance extinction procedure in which shock was inescapable. The rats which had received prior exposure to inescapable shock responded less often and with longer latencies in extinction than did the restrained rats. Experiment 2 demonstrated that this effect is caused by the inescapability of the initial shock treatment. These results were explained in terms of (a) associative interference which minimized the effect of shuttlebox escape training for the preshocked subjects, and (b) a stronger tendency to recognize the presence of an inescapable shock situation during extinction for the preshocked subjects. The relationship between these results and previous work demonstrating that exposure to the escape contingency mitigates the effects of inescapable shock exposure was also discussed.     

The time course of learned helplessness, inactivity, and nociceptive deficits in rats

Four experiments are reported which explore the nature of the effects of inescapable shock on subsequent shuttlebox escape learning. The first experiment demonstrated that shuttle escape deficits dissipate within 48 hr after treatment with inescapable shock. Experiment 2 showed that exposure to inescapable shock suppressed unlearned activity in the shuttlebox and that this activity deficit recovered within 48 hr. Experiment 2A demonstrated that this shuttlebox crossing decrement was at least partly attributable to the inescapability of the shocks. These results suggested that activity factors might partly mediate the shuttle escape learning deficit reported in Experiment 1. Experiment 3 explored the possibility that activity and shuttle escape learning deficits are subserved by the effects of inescapable shock on pain sensitivity. The results supported this notion. It was found that rats were less sensitive to painful stimulation 24 hr after inescapable shock and that this analgesic tendency also dissipated within 48 hr after pretreatment. The implications of these results were discussed.     

Phonatory initiation,termination, and vocal frequency change reaction times of stutterers

Four types of voice reaction times were investigated for eight adult stutterers and eight control subjects using a vocal shadowing paradigm. These were voice initiation and termination reaction times (VIT and VTT, respectively) and voice frequency-shift intiation and termination reaction times (SIT and STT, respectively). Results indicated that the stutterers were slower in VIT, but were as fast as their control subjects in VTT, SIT, and STT. It was suggested that a laryngeal discoordination problem of stutterers lies primarily in the stage of adduction (turning on the voicing) rather than in the stage of abduction (turning off the voicing) or in finer frequency control at the larynx.     

Rate changes in the speech of stutterers after therapy

The fluent speaking rate of nine adult male stutterers was compared before and after stuttering intervention. The subjects, ranging in age from 18 to 37 yr (mean, 25 yr, 3 mo), exhibited mild to severe stuttering prior to treatment. The only rate reduction strategy taught to subjects during intervention was to slow the first phoneme or syllable of sentences spoken. In addition, however, subjects significantly reduced their overall rate as determined by measurements made of their fluent speech at the middle of sentences, as well as overall sentence durations (excepting the first word of utterances). The data from this investigation are interpreted relative to the facilitation/simplification hypothesis.     

Long-term memory in pigeons: I. The role of discrimination problem difficulty assessed by reacquisition measures II. The role of stimulus modality assessed by generalization slope

Pigeons learned either an easy or a difficult line angle discrimination (Experiment 1) or wavelength discrimination (Experiment 2), and then they were given a reacquisition test of retention after delays of 1 min, 1 day, or 1 week. Both percentage of responses to the S+ in the initial 10-trial block and number of blocks to criterion showed a progressive memory loss which was greater for the difficult problem. These results extend recent findings by using a free operant rather than a discrete trial task and by varying problem difficulty by altering the dimensional separation between training stimuli. In Experiment 3, pigeons were given variable interval training with either a wavelength or a line angle stimulus, and then they were tested for generalization in extinction after delays of 1 min, 1 day, and 1 week. With both dimensions, the relative gradients became progressively flatter with increasing delay intervals. This replicates earlier findings and extends them to the line angle dimension. The evidence of substantial forgetting in the first 24 h in all three experiments suggests that operant free-response procedures are more sensitive to forgetting effects than are discrete trial tasks.     

Vocal changes in stutterers and nonstutterers when speaking to children

Within the last few years, considerable attention has been devoted to the possibility that the amelioration of stuttering in many novel speaking conditions is a function of vocal changes with or without accompanying modifications in prosodic expression. These formulations have made reference primarily to conditions in which stutterers were induced into one or another novel speech pattern by an external stimulus such as masking noise, a rhythmic cue, or by instructions to sing, or read in unison with another speaker. In contrast, far less attention has been paid to other ameliorative conditions that lack a novel external stimulus or special instructions that direct the stutterer to speak in some unique manner. Speaking or reading to a child is an example of this latter type of condition. The present study was conducted to see if nine adult stutterers and a matched group of nonstutterers would evince vocal changes as they read aloud to another adult, a child, and a child and adult together. There was also a fourth control condition wherein the subjects read to one of the experimenters. Dependent measures of disfluency and stuttering, fundamental frequency, fundamental frequency deviation, fluent reading rate, and peak vocal sound pressure level were made and treated statistically. The major findings of this study indicated that, relative to the control condition, both subject groups exhibited several vocal changes when reading to a child alone and to a child and adult together. In addition, the stutterers experienced a reduction in disfluency, but only when reading to the child alone. The normal speakers exhibited too few disfluencies in the control condition for any meaningful change to occur in that dependent variable. The fact that the stutterers evinced vocal changes in both experimental conditions but a significant drop in disfluency in just one bears importantly on hypotheses that emphasize vocal changes in conditions that ameliorate stuttering.     

Interactive processes in sentence comprehension and recognition

Two experiments examined the roles played by semantic and surface information in reading and recognizing sentences. Subjects read sentences in normal and inverted typography. Their recognition of meaning and other sentence features was tested using sentences whose typography, wording, and/or meaning were either the same as or different from that in the first set of sentences. In Experiment 1, subjects either read aloud or performed a sentence continuation task. For originally inverted sentences, recognition of meaning was high, irrespective of task demands. For originally normal sentences, recognition was low for Read Aloud subjects and high for Sentence Continuation subjects. Sentence recognition was affected by repetition of wording and typography. Experiment 2 replicated the results with the read aloud task and showed the second reading of originally inverted sentences to be equally swift for paraphrase and verbatim test forms. It was concluded that reading and recognition are interactive processes, involving conceptually driven and data driven operations. The interaction of operations may be either automatic or controlled. While processing of normal typography is automatic, inverted typography induces controlled processing, resulting in better retention. Furthermore, semantic and surface information are conceptualized as interacting components of comprehension and memory processes.     

Vocal changes in stutterers and nonstutterers during high- and low-pitched speech

This study was conducted to provide an indirect test of Wingate's “modified vocalization” hypothesis. In this formulation, the improved fluency that stutterers experience in various novel conditions is attributed to changes in the key correlates of stress, namely, fundamental frequency, vocal SPL, and rate.Normal speakers and stutterers read aloud in an habitual condition following instructions to read at higher- and lower-than-normal pitches. Objective measures were taken of subjects' fundamental frequency, fundamental frequency deviation, vocal SPL, and fluent reading rate. Disfluences were also counted. Findings showed that both stutterers and normals altered several features of voicing from the habitual to the two experimental conditions. Significant condition main effects emerged for fundamental frequency deviation, vocal SPL, fluent reading rate, and disfluency. The only meaningful between-group difference noted showed that the stutterers were more disfluent than the normals across all conditions. Results were interpreted as supporting Wingate's “modified vocalization” position and were discussed relative to how the vocal changes observed might act to promote fluency.     

Spatial perspective taking in young children.

Four- and five-year-old children were tested in a spatial perspective task employing a production format. They were shown a photograph of an aspect of a doll house and asked to generate the view on the photograph for a puppet that served as the observer. The house was mounted on a lazy Susan and could be rotated freely by the children. Puppet line of regard (to a corner, side, or rear of the house) and photograph type (fron, corner, side, or rear) constituted within-subject factors. Puppet position, photograph type, and age affected patterns of errors and proportion of correct responses. It was concluded that perspective taking is highly task dependent as well as dependent upon developmental status.     

A process model for water jug problems

We develop and evaluate a model for the water jug task in which a subject is required to find a sequence of moves (pouring operations) which produce a specified amount of water in each jug. Experiment 1 was designed to evaluate the meansends, move selection heuristics that are assumed by the model. Experiment 2 tested the model's predictions concerning those aspects of the water jug task that determine problem difficulty.A three stage process model incorporating GPS-like, means-ends heuristics and assumptions concerning the utilization of short- and long-term memory was able to account for differences across problems as well as details of the performance of subjects solving a given problem. We conclude that a GPS-like model that only selects one move at a time (no forward planning of move sequences or setting up of subgoals) can provide a good account of solution behavior in the water jug task.     

Learned helplessness and the schedule-shift hypotheses

The critique of learned helplessness research and theory and the alternative schedule-shift discrimination hypothesis offered by McReynolds (Journal of Research and Personality, 1980,14, 139–157) are considered. Each point made by McReynolds is discussed and a variety of recent experimental evidence is reviewed. It is concluded that McReynolds' critique is without substance and that the schedule-shift discrimination explanation of the learned helplessness effect is contradicted by existing data.     

Therapy and immunization of long-term analgesia in rats

Three experiments are reported which examine the effects of experience with escapable shock either subsequent to (Experiment 1) or prior to (Experiments 2 and 3) a session of inescapable shock on the subsequently produced long-term analgesic reaction in rats. Experment 1 demonstrated that experience with escapable shock 4 hr after a session of inescapable tail shock completely reverses the analgesic response that is normally observed 24 hr later upon reexposure to shock. The escapability of the shock was shown to be the important factor in reversing the analgesic reaction, since subjects given inescapable shock in amounts equivalent to escape subjects exhibited no reduction in analgesia. Experiment 2 showed that experience with escapable shock 4 hr prior to a session of inescapable tail shock could also completely eliminate the long-term analgesic reaction. Experiment 3 replicated the results of Experiment 2, but employed a different escape task and temporal parameters in order to extend the generality of the findings, and to more closely match the procedures employed in behavioral experiments reported by J. L. Williams and S. F. Maier (Journal of Experimental Psychology: Animal Behavior Processes, 1977, 3, 240–253). The implications of these results for the areas of pain control and learned helplessness were discussed.     

Categorical and spatial modes of representation in young children's recall

Preschool children aged 4 and 6 were asked to recall a set of line drawings under two conditions: pictures blocked in category groups, and pictures blocked in noncategory groups. For 4-year-olds, the blocking condition made no difference in the structure of their recall; but for the 6-year-olds, the category blocking served as a support for category clustering of their recall lists. No purely spatial clustering appeared at either age. It was concluded that 6-year-olds' use of classes is closely linked to concrete spatial arrangement of objects.     

Relationships between perceptual and conceptual mediational systems in young children

Children aged 48–77 months were afforded experience in either color oddity or nominal class sorting prior to a transfer task testing the ability to apply the oddity rule (“which one doesn't belong”) to three picture arrays where solution was based on nominal class membership. The youngest children in the sample did not benefit from either perceptual rule experience or nominal sorting experience. Subsequent age groups benefited first from the nominal sorting treatment, then from both perceptual rule and nominal sorting activities, and finally the older children did not require priming in either the perceptual or nominal domain for success on the transfer task.     

A model of problem solving with incomplete constraint knowledge

The problem-solving behavior of subjects presented with a series of Tower of Hanoi problems is examined. A production system model which incorporates elements of domain-specific knowledge into a general problem-solving framework is presented. Other models developed for the task are based on understanding of complete solution strategies and are not satisfactory models of nonexpert human performance. The current model discriminates between problem-solving behavior based on constraint knowledge and behavior based on nonspecific general search strategies. A variety of move choice and latency measures are used to compare the performance of the model to human subject performance.     

A process model for Missionaries-Cannibals and other river-crossing problems

We extend a model originally developed by Atwood and Polson (1976) for the water jug task to four isomorphs of the Missionaries-Cannibals problem. Our results show that variation in cover story produced no differences in number of legal moves to solution, but caused large differences in illegal moves. A three-stage process model incorporating means-ends heuristics, assumptions about the utilization of memory, and an illegal move-detection process is able to account for both legal and illegal move data from all four versions of the problem.