Discriminative stimulus control and the effects of concurrent operants.

Discriminative-stimulus-control functions were investigated in a concurrent operant context. Variable-interval reinforcement schedules were arranged for pigeons on two response keys. One key, illuminated with a white vertical line on green background (position irrelevant), was programmed with a given schedule value across groups. For different groups of pigeons, the alternative key, illuminated with green alone, was programmed with twice, the same, or half the reinforcement frequency of the other key. Stimulus-control gradients were collected from both keys as line orientation was varied. On the green-plus-line alternative, flattest gradients were observed when twice the reinforcement frequency was concurrently programmed and the steepest were observed when equal values were concurrently programmed. Also examined were the effects of a programmed changeover delay, important in maintaining the independence of concurrent operants. The changeover delay was found to have relatively minor effects upon stimulus control, despite its typical and marked effects upon steady-state responding.     

THE EFFECTS OF INSTRUCTIONAL MATCH AND CONTENT OVERLAP ON GENERALIZED READING PERFORMANCE

This study examined the effects of instructional match and content overlap on students' ability to generalize from passage reading instruction. Four students with mild disabilities served as participants. Using a multielement design, students were instructed with passages at two levels of text difficulty (instructionally matched vs. instructionally mismatched), and generalization was assessed with passages at two levels of similarity to those instructed (low vs. high content overlap). Results indicated that students' oral reading accuracy and fluency showed the greatest degree of generalization when instructional materials were matched to the students' skill level and assessment materials were similar to those used during instruction. Moreover, these results were maintained at 1-month follow-up. The implications of these findings for classroom reading instruction and the assessment of students' reading skills are discussed.     

Stimulus generalization from feeder to response key in the acquisition of autoshaped pecking

During autoshaping, a 6-second presentation of one stimulus and a variable time 30-second presentation of a second stimulus alternated in appearance on a pigeon key. Grain always was delivered for 3 seconds at the end of the first stimulus interval. In the first experiment, autoshaped pecking of the stimulus preceding grain delivery began much sooner when that stimulus was a black vertical line on a white background and the other stimulus was green than when the opposite stimulus arrangement was used. Because these two stimuli differed in form, hue, brightness, and similarity in hue and brightness to the illumination of the raised feeder, three subsequent experiments examined whether the differential speed of autoshaping in the two groups was due to a feature-positive, feature-negative effect, a preference for brighter over darker stimuli, a simple preference for white over green, or stimulus generalization from the brightness or hue of the illuminated, raised feeder to the stimulus on the key preceding grain delivery. The data from these experiments showed that the first autoshaped key peck was most likely to be made to the stimulus of the same hue as that illuminating the feeder, regardless of whether that stimulus was positively or negatively associated with grain delivery. At least under some conditions, therefore, stimulus-generalization mediated response transfer of pecking grain in the presence of the hue illuminating the feeder to pecking the key illuminated by a similar hue appears to account for the occurrence of autoshaped key pecking.     

TEACHING NAMING OF COIN VALUES—COMPREHENSION BEFORE PRODUCTION VERSUS PRODUCTION ALONE1

The purposes of this experiment were to determine whether (a) it would require fewer trials to teach verbal production of coin values directly or to teach auditory comprehension first, (b) comprehension training would generalize or transfer to production, and (c) production training would generalize to comprehension. Fourteen mentally retarded subjects participated. Their mean mental age was 4.83 yr (SD = 1.83), their mean chronological age was 12.67 yr (SD = 3.17), their mean IQ was 43.86 (SD = 7.81), and their mean arithmetic grade level was Kindergarten 0.1. A matched groups pretest-posttest design, as well as a multiple baseline across responses within each group were employed. The Comprehension-Production Group received coin-value training using two procedures sequentially: auditory comprehension (pointing to the correct coins in response to their verbally stated value) followed by verbal production (verbally stating the coins' value in response to a pointing prompt). The Production Group was trained on the production procedure only. Each subject was repeatedly administered coin-value comprehension and coin-value production tests, which provided the dependent measures. The results indicated that the two experimental groups improved significantly in their comprehension and production of coin values from pretest to posttest and maintained those increments on one- and four-week followup tests. Mean group performance on four-week followups ranged from 89 to 96% correct for the two dependent measures and two groups. Multiple-baseline data showed pronounced increases in performance only after training was initiated on a particular coin. A comparison of the number of trials required for both groups to complete their respective training programs indicated that teaching production alone (X? trials = 137.42) was significantly more efficient than training both comprehension and production (X? = 281.71). The failure of the comprehension procedure to facilitate production acquisition was evidenced by the fact that the Comprehension-Production Group required as many verbal naming trials to achieve mastery as did the Production Group. On the other hand, there was generalization from production training to comprehension. Subjects in the Production Group who were not trained to point to the coins in response to verbal instruction averaged 99% correct on the comprehension test. Research to this point may suggest an interaction between mental level and direction of transfer. The mentally retarded may experience facilitation from production to comprehension training, and for the nonretarded, the direction of transfer may be the converse.     

Stimulus duration as a measure of stimulus generalization

Four pigeons in the line-positive group were trained with a vertical line on a green background that signalled intermittent reinforcement while a plain green field signalled extinction. Four pigeons in the line-negative group were trained with the opposite discrimination. Response to a control key terminated any trial and initiated the next trial. The birds also used the control key during generalization tests to control the durations of trials in which various line orientations were presented. These durations were summed to provide generalization gradients of stimulus duration that were positive or negative in accordance with the trained discriminations. In Experiment 2, birds from the line-positive group were tested with a procedure in which the control key was not available on some trials. This provided an independent assessment of response rates to the test stimuli. These rates were used to predict the stimulus durations obtained when the control key was available. The findings supported a general model for the prediction of response distributions among concurrent stimuli from rates observed with single stimuli.     

SETTING GENERALITY AND STIMULUS CONTROL IN AUTISTIC CHILDREN1

This study was designed to assess the transfer of treatment gains of autistic children across settings. In the first phase, each of 10 autistic children learned a new behavior in a treatment room and transfer to a novel extra-therapy setting was assessed. Four of the 10 children showed no transfer to the novel setting. Therefore, in the second phase, each child who failed to transfer participated in an analysis of stimulus control in order to determine the variables influencing the deficit in transfer. Each of the four children who did not transfer were selectively responding to an incidental stimulus during the original training in the treatment room. Utilizing a reversal design, each of the four children responded correctly in the extra-therapy setting when the stimulus that was functional during training was identified and introduced into the extra-therapy setting. The extreme selective responding and the resulting bizarre stimulus control found are discussed in relation to the issue of setting generality of treatment gains.     

DEVELOPMENT OF SPONTANEOUS MANDING IN LANGUAGE DEFICIENT CHILDREN

Six institutionalized children, aged 7–11, with little or no spontaneous vocal manding, were trained to request food items under appropriate natural conditions when snacks were presented. “I want a” was appropriate when an adult presented food in the playroom. “Out” was appropriate when the items were displayed in the hallway, across a half-door barrier from the child. A sequence of steps was trained, through increasingly naturalistic setting and cuing conditions. The two mands were trained in sequence, not concurrently. To encourage “spontaneous” productions, no vocal cuing was provided by the adult. After criterion performance in each step, several probe sessions were conducted for various cuing conditions, adults, and settings. Probes after imitation training showed no spontaneous manding. Thus, failure of manding was not due to production difficulties. In probes after training for “approximately” natural cues, most children showed little transfer to the natural cues. This implies that training for the specific appropriate cues may often be required. However, good transfer generally occurred across persons, and from training room to playroom. Probes also showed that most children did not use one of the trained mands in the stimulus conditions that were appropriate for the other mand. Thus, adding a second mand did not generally disrupt use of the first. However, significant disruption occurred for two children. Finally, at the end of training, extinction training was given for one mand in one setting. Performance of the other mand was litle affected. In sum, the appropriate form of a mand depends on specific stimulus and setting characteristics, and these characteristics must be considered in training.     

STACKING THE DECK: TEACHING SOCIAL SKILLS TO RETARDED ADULTS WITH A MODIFIED TABLE GAME

This study developed and evaluated a social skills training program for institutionalized mildly or moderately retarded and dually diagnosed individuals. Social skills were conceptualized as requiring an action or reaction within six skill areas: compliments, social interactions, politeness, criticism, social confrontation, and questions/answers. The program taught social skills using a commercially available table game, Sorry, and a specially designed card deck. Each card represented one of the skill areas and was designed to train either an actor or reactor response. The program featured response specific feedback, self-monitoring, individualized reinforcers, and individualized performance criterion levels. A multiple baseline across two groups (N = 3 per group) revealed that the game contingencies increased social skills in all targeted areas. After training, the subjects displayed their newly learned skills at or above their trained levels in two different settings with novel persons present. Although untargeted, the complexity of the subjects' responses increased across conditions, since there was a steady increase in the number of words they used per response. The program appears to be a viable means of training social skills since it uses standardized training procedures, requires only one facilitator, and is in itself a social situation that may encourage interactions with peers, cooperation, competition, and politeness.     

INCREASING VERBAL INTERACTION AMONG ELDERLY SOCIALLY ISOLATED MENTALLY RETARDED ADULTS: A GROUP LANGUAGE TRAINING PROCEDURE

The present study examined the effectiveness of a group language training procedure for directly increasing and generalizing the rate of verbal interaction among four elderly, socially isolated, moderately mentally retarded men. A withdrawal of treatment design was used to examine the effect of the procedure that used verbal prompts, behavioral rehearsal, and contingent social praise. Changes in behavior were examined in two generalization settings, one similiar to the training environment (Generalization I) and the other arranged as part of the subjects' daily routine (Generalization II). Baseline data indicated no verbal interaction among the subjects. During treatment the training procedure increased the rate of subjects' verbal interactions not only in the training situation, but also in the two generalization settings. An analysis of the data obtained during the Generalization II situation indicated that subjects' verbal interaction increased not only among themselves, but with nonsubject peers present in this setting. Follow-up data showed that increases in rates of verbal interaction were maintained four months after the cessation of training. The implications of the results for program generalization and work with the language deficient individual is discussed.     

The nucleus basalis and memory codes: auditory cortical plasticity and the induction of specific, associative behavioral memory

Receptive field (RF) plasticity develops in the primary auditory cortex (ACx) when a tone conditioned stimulus (CS) becomes associated with an appetitive or aversive unconditioned stimulus (US). This prototypical stimulus-stimulus (S-S) association is accompanied by shifts of frequency tuning of neurons toward or to the frequency of the CS such that the area of best tuning of the CS frequency is increased in the tonotopic representation of the ACx. RF plasticity has all of the major characteristics of behavioral associative memory: it is highly specific, discriminative, rapidly induced, consolidates (becomes stronger and more specific over hours to days) and can be retained indefinitely (tested to two months). Substitution of nucleus basalis (NB) stimulation for a US induces the same associative RF plasticity, and this requires the engagement of muscarinic receptors in the ACx. Pairing a tone with NB stimulation actually induces specific, associative behavioral memory, as indexed by post-training frequency generalization gradients. The degree of acquired behavioral significance of sounds appears to be encoded by the number of neurons that become retuned in the ACx to that acoustic stimulus, the greater the importance, the greater the number of re-tuned cells. This memory code has recently been supported by direct neurobehavioral tests. In toto, these findings support the view that specific, learned auditory memory content is stored in the ACx, and further that this storage of information during learning and the instantiation of the memory code involves the engagement of the nucleus basalis and its release of acetylcholine into target structures, particularly the cerebral cortex.