Stimulus probability and prediction outcome as determinants of choice reaction time: Some procedural considerations

Effects of stimulus probability and prediction outcome on two-choice reaction speed (CRS) were determined when a frequency imbalance was reversed half-way through 300 samples of a 70/30 stimulus distribution and when the same 70/30 distribution was sampled for 1200 trials. Prior to each presentation Ss made a prediction; following each presentation Ss identified the stimulus by pressing a right-hand or left-hand trigger. CRS was faster to correctly predicted stimuli, and faster to the more probable stimulus. Ss who were informed of the frequency imbalance reacted significantly faster than Ss who were not. Both practice and boredom effects were demonstrated by using the extended number of trials. CRS was faster during the second session of 300 trials than during the first; after two sessions, CRS was slower during the second half of two additional sessions.     

Responding time: A response equivalent to inspection time

A response equivalent to ‘inspection time’ (IT) was developed using a reaction time task in which Ss were required to respond as quickly and accurately as possible to whichever one of two lights appeared on each of a number of trials. The appearance of the lights was followed on all trials by a backward mask. IT was estimated for each S as the shortest duration between the onsets of the light and the backward mask at which the S could respond accurately on virtually every trial. An estimate of ‘responding time’ was then made by setting the duration between the stimulus onset and the mask to each S's individual IT and gradually reducing the time between trials so that Ss had less and less time in which to respond correctly. Responding time was taken to be the shortest such interval at which the S could respond accurately on virtually every trial. This measure was found to be reliable although quantitatively different estimates were obtained using two different methods of presenting the stimulus trials. Responding time was longer for a group of lower-intelligence Ss than for a group of higher-intelligence Ss and the measure was also found to correlate with measured intelligence in the former group. However, it did not itself correlate significantly with IT suggesting that responding time and IT may be measuring different underlying processes.     

Hypotheses,strategies, and stereotypes in discrimination learning

In the course of two experimentss groups of kindergarten, second, fourth, sixth grade and college students received several discrimination problems. Each trial with feedback was followed by a series of blank trials, which served as a probe for S's hypothesis. Ss responded systematically during the blank trials on about 90% of the probes. Beginning at the second grade they typically showed characteristic hypothesis-testing behavior, viz., keeping confirmed hypotheses, rejecting those disconfirmed, etc.     

Prediction outcome and choice reaction time: Inhibition versus facilitation effects

In two-choice RT tasks Ss verbally predicted all stimulus presentations, two-thirds of the presentations, or none of the presentations. Effects of stimulus probability were similar for each type of prediction trial: Correct Prediction Outcome (PO), Incorrect PO, and No-Prediction (NP). When comparisons between Prediction and NP trials were between Ss, reactions on NP trials were significantly faster than reactions POs, but were not slower than reactions to Correct POs. However, when Prediction and NP trials occurred within Ss, reactions on NP trials were not faster than reactions to Incorrect POs, but were significantly slower than reactions to Correct POs. Speculations about Ss' implicit stimulus predictions are offered to interpret differential implications of inhibition and facilitation.     

Positive contrast obtained in reacquisition following interpolation of nonreinforced or partially reinforced trials

Two experiments investigated the effects of shifting from either nonreinforcement or partial reinforcement (PRF) to continuous reinforcement conditions (CRF). In the first experiment, three groups of rats were given food reinforcement under CRF conditions in a runway followed by regular extinction trials (RE), extinction trials where Ss were delayed for 30 sec before entering the empty goal box (DE), or CRF trials where Ss were delayed for 30 sec before entering the baited goal box (DF). Then all Ss were run on the delayed reinforcement condition (DF). In the final delayed reinforcement condition, group DE ran significantly faster than group DF, reflecting positive contrast. In the second experiment, four groups of rats were trained in a runway to receive either 4% or 18% sucrose reinforcers under either PRF or CRF conditions. Then all Ss were transferred to a Skinner box and bar presses were continuously reinforced, with each S continuing to receive the same sucrose concentration as before. The former PRF Ss, regardless of the reinforcer, bar pressed at a significantly higher rate in the Skinner box than the former CRF Ss. The evidence seemed to favor the view that the effectiveness of a reinforcer is not an absolute, unchanging quantity but rather depends on the historical context in which the reinforcer occurs.     

Parameters affecting the acquisition of Sidman avoidance

Four studies were conducted to investigate the source of reinforcement of Sidman avoidance. First it was found that the acquisition of avoidance was seriously impaired if there was no immediate stimulus consequence of responding, i.e., proprioceptive and auditory feedback. The second study showed that if the shock-shock interval was split so that only responses occurring in one half of the interval were effective in postponing shock, then learning was impaired. It made little difference which half of the interval was used. The third study demonstrated that Ss learn Sidman avoidance more quickly with a variable shock-shock interval than with the usual fixed-interval procedure. The results of the second and third experiments argue against the view that avoidance is reinforced by the decrease in conditioned aversiveness that occurs at long post-shock times. The final experiment indicated that Ss do not learn Sidman avoidance if the response-produced delay of shock is preceded by a shock, hence it seems unlikely that the crucial source of reinforcement is merely an overall reduction in shock density. All of the findings are consistent with the hypothesis that the avoidance response is reinforced by the decrease in conditioned aversiveness of stimuli at short post-response times. This seems to be the case even at the beginning of acquisition.     

Concept identification with natural material.

Phonetic letters in Japanese (Hiragana, 23 in number) written by 6 adults (Ws) were presented one by one and the S was asked to guess by which W it was written. Immediately after the S made the guess, the code of correct W was given on each trial. The Ss were Japanese housewives, students etc., 53 in number. Rate of correct identification increased during 23 × 6 trials, but only from 0.3 to 0.4 on the average. The learning transferred to the remaining 23 letters of the same kind but not to letters of the other kind (Katakana). On each trial, the S verbally described cues upon which the guess was made. When the data were separately analysed according to Ws, it was found that letters of the W who was most difficult to identify were most ‘diffused’ in characterization by the Ss. The relevance of the present experiment to study of concept identification in general was also discussed.     

Effects of stimulus differentiation training upon hypotheses,strategies, and stereotypes in discrimination learning among kindergarten children

Two groups of kindergarten children received stimulus differentiation training either with feedback (experimental Ss) or without (controls), prior to presentation of a series of discrimination-learning problems using blanktrial probes. Results were as follows: Performance of both groups was virtually perfect during differentiation training (less than one error per 1000 trials). In transfer, however, experimental Ss solved more problems, generated more consistent Ss during blank-trial probes, manifested fewer response sets, were more likely to abandon a disconfirmed H, sampled more locally consistent Ss following errors, and retained a confirmed H more frequently than control Ss. Experimental Ss also manifested strategy Sys (hypothesis sampling systems) predominately, while controls generated only stereotypes. Findings were discussed in relation to theoretical perspectives derived from Piagetian theory and developmental learning theory.     

Dissociation between conditioned emotional response and extended avoidance performance

The present experiments examined the dissociation between the strength of a shuttlebox avoidance response (AR) and one index of fear of the avoidance CS. Avoidance response strength was indexed by resistance to extinction of the AR and by changes in response latency, and fear of the CS was indexed by the conditioned emotional response (CER) technique. Experiments 1, 2A, and 3A all found that rats trained to a criterion of 27 consecutive avoidance responses (CARs) showed response strength comparable or superior to rats trained to a criterion of 9 CARs. Experiments 2B and 3A demonstrated that rats trained to 27 CARs showed less suppression of bar pressing during the avoidance CS (less CER) than rats trained to 9 CARs. Experiment 3A also found that, when extinguished in the shuttlebox to a moderate criterion (5 consecutive trials without a response) before CER testing, rats trained to 9 CARs showed some, although not complete, loss of CER, whereas rats trained to 27 CARs showed no loss of CER. In Experiment 3B rats that took 1 vs 2 days to reach a criterion of 27 CARs were compared for their AR strength and for their CER. Although rats taking 2 days to reach criterion showed somewhat greater resistance to extinction of the AR than rats reaching criterion in 1 day, this variable had no apparent effect on the CER. Implications of the present results for current theories of avoidance learning are discussed.     

Effects of a coactor's prediction on latencies to predict and indentify stimuli

On each of 300 trials E's confederate (C) verbalized which of two stimuli would occur; then S made a prediction. Following each presentation, S and C pulled a trigger to identify the stimulus. Two latencies were measured: the interval between C's and S's prediction (prediction time), and the interval between stimulus presentation and S's identification response (choice RT). Prediction times were significantly shorter when S's prediction agreed rather than disagreed with C's prediction, when S's preceding prediction was correct rather than incorrect, and when S was female rather than male. Choice RT was influenced by distributions of C's stimulus predictions and C's prediction outcomes in directions supporting an expectancy model.     

Paired-associate learning by normal children and retardates with relevant redundant compound stimuli

During daily sessions four first-grade boys each played a two-choice marble dropping game. When one colored light was presented a plain token was dispensed as soon as S dropped a marble, and when another light was on a token with a hole in its center was delivered. During choice trials that were interspersed among single-color trials S had to choose one of the two different colored holes. At the end of each session S traded tokens with holes for pennies and then turned in the remaining plain tokens which were not exchanged for money. After S had developed a preference for the response that earned the tokens with holes (tokens that were backed up with pennies) E instructed S to try to get as many plain tokens (unexchangeable tokens) as he could. All Ss immediately switched to the response that earned unexchangeable tokens but as soon as E left they returned to choosing the backed up response. When the adult reentered, Ss again chose to work for unexchangeable tokens. Two different Es (male and female) served and the instructions of each were effective in controlling responding as long as the adult was present, except for one S who did not respond to one E, but did respond as described for the other.     

Developmental changes in apportionment of study time among items in a multitrial free recall task

First grade, third grade, and college Ss attempted to memorize a single set of items over the course of 5 trials, each trial consisting of a 45-sec study period followed by a free recall test. On all trials but the first, S was allowed to have available during his study period only half of the total set of items, but was free to select whichever items he wished to include in this half. Third grade and college Ss were significantly more prone than first grade Ss to select for study items not recalled in the immediately preceding recall test. The results suggest that the strategy of deliberately concentrating one's study activities on the less well mastered segments of materials to be learned, like other elementary memory strategies (e.g., rote rehearsal), cannot automatically be assumed to be part of a young child's repertoire of learning techniques.     

Return of fear: The role of inhibition

In a previous study investigating the relationship between subjective, physiological and behavioural changes during treatment of specific phobias, a marked between-session increase was found in subjective fear after high, but not after low intensity phobic stimulation although the groups showed similar fear ratings and heart rates immediately after treatment (Grey et al, 1979). It was hypothesized that the high intensity stimulation led to ‘treatment fatigue’; a state of deactivation, the recovery from which led to a return of fear.In this study high intensity in vivo stimulation was used for the treatment of phobic subjects under conditions of distributed and massed practice. No differences emerged between treatment conditions. A small group of Ss with a conspicuously high heart rate (mean level 120 bpm) when rating zero fear, showed a significant increase in fear after one week's interval, although they had shown similar improvement to the Ss during treatment. Subjects in both treatment conditions showed lower heart rate at all post-treatment assessments than pre-treatment. The high initial heart rate Ss continued to have higher heart rate than other Ss throughout the experiment, although they showed a decrease after treatment. It was only these Ss with desynchronously high heart rate, i.e. high heart rate with zero fear ratings, who suffered a return of fear, whereas high heart rate during high fear did not predict either response to treatment or return of fear. A further finding was a lack of correlation between the behavioural and physiological indices of fear, namely, between distance and heart rate at high levels of fear.     

Dissociative effects of different types and amounts of nonreinforced CS exposure on avoidance extinction and the CER

Two experiments examined the effectiveness of two amounts of flooding or response-prevention on hastening avoidance response extinction and on reducing CS-produced suppression of bar-pressing for food. In Experiment 1, 20 and 30 flooding trials were both shown to be effective in hastening the extinction of a well-learned shuttlebox avoidance response. In Experiment 2, rats trained under comparable conditions to those in Experiment 1 were tested following flooding for the CER in a different apparatus. The results indicated that 30, but not 20, flooding trials were sufficient to reduce the CER. In each experiment the results of additional control groups equated with the flooded groups for nonreinforced CS exposure also revealed a dissociation between the effectiveness of this CS time control procedure in hastening avoidance response extinction and in reducing the CER. Further comparisons showed that although 30 flooding trials did reduce the CER, the same total duration of nonreinforced CS Exposure in the form of avoidance extinction trials did not. Thus the context in which CS exposure occurs may affect the dynamics of extinction of the CER. The experiments are discussed in the broader context of dissociation of various indices of fear in humans.     

Detection of Malingering of Psychiatric Disorder With the Personality Assessment Inventory: An Investigation of Criminal Defendants

582 Ss in 8 experiments viewed 1 of 9 films portraying models involved in achievement (Ach), affiliation (Aff), or neutral (Neu) activity. Ss who viewed Ach models after an interval of adaptation to the setting produced more TAT n Ach immediately after the film than other adapted Ss. Under other conditions, Ss who viewed Ach models produced significantly less n Ach than Ss who viewed non-Ach models. Results were ordered to a “subself” conception of personality organization and three theoretical propositions: (a) Models elicit fantasy thematically similar to their activity unless S is incompatibly preoccupied, (b) in which case models cause suppression of similar fantasy; but (c) in fantasy both elicitation and suppression are short-lived.     

Two experiments on the relation between psychoticism and response uncertainty in normal subjects

Previous studies have suggested that schizophrenics are affected by response uncertainty to a greater degree than normals or other psychiatric groups. Two studies examined whether a similar pattern of performance would be produced in normal Ss scoring high on questionnaire measures presumed to measure psychotic predisposition. The Psychoticism (P) scales from the EPQ and the unpublished PEN Inventory were employed; and response uncertainty was varied using a card-sorting procedure. In Experiment 1 males were more affected by increases in response uncertainty than females, but there was no difference between Ss scoring high and low on the P scales. Experiment 2 included a condition in which guide-cards were randomly reordered between trials. There was a highly significant tendency for Ss scoring high on the PEN P scale to be more affected by response uncertainty in this experiment. Again males were more influenced by uncertainty than females, but this was due largely to their performance under the condition where guide-cards were varied. Ss high on EPQ P also showed decremental performance under this condition. The data provided partial support for the validity of the P scales, particularly the PEN version of the scale, as indices of schizophrenic predisposition.     

Effectiveness of debriefing after a stress-producing deception

This experiment was carried out to determine if after deceiving Ss an E had sufficient credibility to effectively debrief the Ss. Ss in two stress groups were given false information indicating that when a signal light came on they would receive painful electric shocks. Ss in a no-stress group were not told about shocks. After being given the threatening instructions, Ss in one of the stress groups were debriefed concerning the deception (but the “shock electrodes” were not removed) while Ss in the other group were not debriefed. After this the signal light came on for all groups. Arousal was measured by pulse rates and self-reports. The results revealed that (a) the instructions about electric shocks increased the arousal levels of the two stress groups relative to the no-stress group, thus indicating that the deception was effective, and (b) after the signal light came on the stress group which had not been debriefed continued to show a high degree of arousal while the stress group which had been debriefed showed a reduction of arousal to the same low level of arousal as the no-stress group, thus indicating that the process of debriefing had been effective.     

Individual Interpretation Of Psychoneurotic Inventory Items

The usual finding of greater resistance to extinction (Rn) following partial reinforcement (PR) as compared to continuous reinforcement (CR) has not been well documented with the use of human S s in instrumental conditioning. One hundred twenty male and female college students practiced discrete trials on the pursuit rotor. Resistance was measured by the number of trial S was willing to continue under instructions that S would terminate the experiment. Those S s receiving knowledge of results during 25%, 50%, or 75% of the first 24 trials showed greater Rn (p < .01) than Ss receiving knowledge of results on all 24 trials.     

The effects of language conditioning on various aspects of anxiety

Staats' three-function learning theory provides the basis for investigating the effects of emotionally-relevant self-verbalizations (SV) on the physiological, subjective-affective and behavioural aspects of anxiety. Using aversive electric UCSs and slides of snakes (CS), anxiety was classically conditioned in 88 volunteer Ss. In 20 subsequent language-conditioning trials (without aversive electric UCSs), the same snakes slides were paired with UCS verbalizations having either positive or negative connotative meanings. Half of the Ss were exposed to a living snake prior to language conditioning. The results show a complete extinction of the conditioned anxiety response in groups with positive SV whereas negative SV impeded extinction; the latter effect could only be found in groups without exposure to snakes prior to language conditioning. In general, the affective evaluation of snakes improved in groups with positive SV and deteriorated in groups with negative SV. However, these effects were more pronounced in groups without exposure to snakes. Although the results indicate that Ss in all groups with positive SV exhibited more approach behaviours than Ss with negative SV, this trend was not statistically significant. The possible relevance of the results for a language-conditioning approach to anxiety reduction is briefly discussed.