The role of verbal behavior in human learning: II. Developmental differences

When children in four different age ranges operated a response device, reinforcers were presented according to fixed-interval schedules ranging in value from 10 to 70 seconds. Only the behavior of the subjects in the youngest of the four groups, the preverbal infants, resembled that of other animal species. The children in age ranges 5 to 6½ and 7½ to 9 years exhibited either the low-rate or high-rate response patterns typical of human adults. Those who showed the low-rate pattern reported a time-based formulation of the contingencies and some of them were observed to occasionally count out the interval before responding. The performance of children aged 2½ to 4 years differed from that of both infants and older children, though containing some patterning elements similar to those produced by the older and younger subjects. The predominant response pattern of the infants consisted of a pause after reinforcement followed by an accelerated rate of responding that terminated when the next reinforcer was delivered. Analysis of postreinforcement-pause duration and response rate showed that infant performance, but not that of the older children, consistently exhibited the same kinds of schedule sensitivity observed in animal behavior. The evidence supports the suggestion that the development of verbal behavior greatly alters human operant performance and may account for many of the differences found between human and animal learning.     

Human fixed-interval performance with concurrently programmed schedules: A parametric analysis

Young adults pressed a lever for points, exchangeable for money, programmed on concurrent schedules in which one component was a fixed-interval and the other component either a fixed-ratio (Experiment 1) or a differential-reinforcement-of-low-rate (Experiment 2). Two general patterns of fixed-interval responding, postreinforcement pause or constant rate, occurred in both experiments as a function of the parameter values of each component. Also patterns of interaction between the component schedules developed, in which responding or point delivery on one component appeared to be discriminative for responding on the other component. Once a pattern of responding was established, it tended to persist when the parameter values of the schedule were changed. On many schedules, subjects with an experimental history responded differently than did naive subjects, although certain schedule values were resistant to the history effects. The role of verbal strategies in mediating history effects was discussed.     

Some effects of response-correlated increases in reinforcer magnitude on human behavior

After training under short or long fixed-interval schedules, humans responded under a modified fixed-interval schedule in which magnitude of reinforcement (X or 2X) was minimally correlated with response frequency. Response frequencies that equaled or exceeded a minimum response criterion were followed by the larger reinforcer at the end of the interval; otherwise, the smaller reinforcer was delivered. The modified schedule alternated with the baseline schedule across conditions. In a control condition, the reinforcer magnitudes produced by control subjects were yoked to those of experimental subjects. Experimental subjects, but not control subjects, showed increased responding. In addition to the baseline and modified fixed-interval schedules used in Experiment 1, subjects in Experiment 2 also responded under a second modified fixed-interval contingency in which increases in reinforcer magnitude were more highly correlated with response frequency. Experimental subjects, but not control subjects, showed increased responding under both procedures. Direct comparison of these two procedures showed that the high-correlation procedure produced greater increases in responding than did the low-correlation procedure.     

Effects of differences in interreinforcer intervals between past and current schedules on fixed-interval responding

Undergraduates were exposed to a mixed fixed-ratio differential-reinforcement-of-low-rate schedule. Values of the schedule components were adjusted so that interreinforcer intervals in one component were longer than those in another component. Following this, a mixed fixed-interval 5-s fixed-interval 20-s schedule (Experiment 1) or six fixed-interval schedules in which the values ranged from 5 to 40 s (Experiment 2) were in effect. In both experiments, response rates under the fixed-interval schedules were higher when the interreinforcer intervals approximated those produced under the fixed-ratio schedule, whereas the rates were lower when the interreinforcer intervals approximated those produced under the different-reinforcement-of-low-rate schedule. The present results demonstrate that the effects of behavioral history were under control of the interreinforcer intervals as discriminative stimuli.     

The role of verbal behavior in human learning: III. Instructional effects in children

Lever pressing of children from three age groups (2½ to 4, 5 to 6½, and 7½ to 9 years) could produce reinforcers according to a fixed-interval 40-s schedule: (1) Some were instructed to respond at a high rate, others at a low rate, and (2) they were subsequently taught to provide their own spoken self-instructions consonant with the earlier, experimenter-supplied instructions. All subjects who received high-rate instructions responded at a steady, high rate, which was maintained following self-instructional training. The effects of low-rate instructions were directly related to the age of the children. The two older groups produced low-rate patterns, with the oldest children responding at very low rates; effects were least noticeable in the youngest age group. Following self-instructional training, all three groups showed adult-like low-rate behavior and the oldest children showed an improved ability to estimate the interval length. The results provide further evidence of the importance of language as a determinant of human behavior.     

Low-response-rate conditioning history and fixed-interval responding in rats.

Bar presses by one group of rats were conditioned under a differential-reinforcement-of-low-rate reinforcement schedule immediately prior to conditioning under a fixed-interval schedule. In a second group of rats, bar presses were conditioned first under a differential-reinforcement-of-low-rate schedule and then under a fixed-ratio schedule prior to conditioning under a fixed-interval schedule. Low response rates occurred under the fixed-interval schedule only when it was immediately preceded by low-rate conditioning. Otherwise, fixed-interval responding was similar to responding under the fixed-ratio schedule. This finding suggests that responses of laboratory animals are sensitive to immediate history, and, unlike human responses, are relatively insensitive to a history of low-rate conditioning when it is followed by high-rate conditioning.     

Individual differences in working memory strategies for reading expository text

This study investigated whether individual differences in working memory (WM) span are associated with different WM management strategies during the reading of expository text. In Experiment 1, probe questions were presented on line during reading to determine whether thematic information was maintained in WM throughout comprehension. The data indicated that readers across the range of WM span maintained thematic information in WM throughout the reading of a given passage. In Experiment 2, sentence reading times and accuracy for both topic and detail questions were measured in two conditions: when topic sentences were present and when topic sentences were absent. Subjects performed similarly across the range of WM span in the topic-present condition, but lower span subjects performed more poorly on detail questions in the topic-absent condition. In Experiment 3, the topic-present condition of the second experiment was replicated, except that subjects expected to receive questions about details only. Thematic processing and retention of topic and detail information all increased with span. Taken together, these results suggest that, for more difficult text processing tasks, high- and low-span subjects adopt different WM management strategies and these strategies influence what is learned from reading the text.     

Handwriting as an operant

An apparatus was designed to monitor handwriting behavior. Two subjects were studied under various schedules of monetary reinforcement for handwriting. The different schedules engendered and maintained distinctive response patterns but the rates of sustained responding did not vary across schedules. The development of fixed-interval performance following continuous reinforcement resembled the same transition in lower animals. In one subject, availability of reading material interacted with the schedule to determine response pattern. It was suggested that handwriting may be a more appropriate response for the experimental analysis of human behavior than the more frequently used button-pushing or lever-pulling responses.     

Auditory location as an encoding dimension.

In two experiments, subjects were given five successive short-term memory tests. In Experiment 1, recall was not significantly facilitated when memory material in the final test was delivered to the ear opposite to the one that received the memory material in the four preceding tests. In Experiment 2, events were presented from two differentially located speakers rather than through headphones. A shift across speakers on the final test did produce proactive interference release. These findings suggest spatial location as a potential encoding dimension of verbal material.     

Second-order schedules: discrimination of components

Pigeons were exposed to a series of second-order schedules in which the completion of a fixed number of fixed-interval components produced food. In Experiment 1, brief (2 sec) stimulus presentations occurred as each fixed-interval component was completed. During the brief-stimulus presentation terminating the last fixed-interval component, a response was required on a second key, the brief-stimulus key, to produce food. Responses on the brief-stimulus key before the last brief-stimulus presentation had no scheduled consequences, but served as a measure of the extent to which the final component was discriminated from preceding components. Whether there were one, two, four, or eight fixed-interval components, responses on the brief-stimulus key occurred during virtually every brief-stimulus presentation. In Experiment 2, an attempt was made to punish unnecessary responses on the brief-stimulus key, i.e., responses on the brief-stimulus key that occurred before the last component. None of the pigeons learned to withhold these responses, even though they produced a 15-sec timeout and loss of primary reinforcement. In Experiment 3, different key colors were associated with each component of a second-order schedule (a chain schedule). In contrast to Experiment 1, brief-stimulus key responses were confined to the last component. It was concluded that pigeons do not discriminate well between components of second-order schedules unless a unique exteroceptive cue is provided for each component. The relative discriminability of the components may account for the observed differences in initial-component response rates between comparable brief-stimulus, tandem, and chain schedules.     

Variable-ratio conditioning history produces high- and low-rate fixed-interval performance in rats

Four rats were exposed to an A-B-A-B series of 30 sessions each of variable-ratio 20 (A) and fixed-interval 30-s (B) schedules. Four other rats received 120 sessions of fixed-interval 30 s. The rats with a history of variable-ratio responding subsequently showed primarily high or low response-rate patterns on the fixed-interval schedule without evidence of classical scalloping (i.e., increased rates of responding throughout the interreinforcement interval), except infrequently in 1 rat. The rats exposed to only the fixed-interval 30-s schedule displayed the expected sequence of scalloping giving way to lower rate break-run or simply low-rate responding over time. This experiment shows that when naive rats are exposed to even a simple history of reinforcement (in this case, a variable-ratio 20), their subsequent fixed-interval performance is very different from comparable performance in naive rats, and might be said to be more similar to the responding of adult humans. The argument is made that care should be taken in comparing the fixed-interval performance of humans and nonhumans because humans have a complex history of reinforcement, whereas laboratory nonhumans are typically naive.     

Human performance on conjunctive fixed-interval fixed-ratio schedules

Eighteen young adults performed a lever-pulling task for money. Subjects were initially exposed to a fixed-interval 80-second schedule and subsequently to one of three conjunctive schedules in which the added fixed-ratio requirement was set at either 10, 80, or 120 responses. Three fixed-interval response patterns emerged: high constant rate, intermediate rate, or low rate, with most subjects displaying the last. Conjunctive performance was related to the subjects' prior fixed-interval patterns and the conjunctive ratio requirements. Low-rate subjects tended to optimize reinforcement (maximum reinforcers for minimum responses) on conjunctive schedules. Response rate was directly related to ratio requirements. Subjects' performance closely corresponded to their verbal statements of the contingencies.     

Verbal and pictorial elaborations enhance memory in younger and older adults

Abstract

These studies examined the facilitative role of verbal and pictorial elaborations in younger and older adults' recall of verbal material. During acquisition, subjects studied short sentences under one of several encoding/retrieval conditions where the presence of verbal and pictorial elaborations was systematically varied. Subjects later recalled the target adjectives, given the sentence frames as a prompt. In Experiment 1, explanatory verbal elaborations at study and test enhanced verbal recall for both age groups, but no benefit of pictorial elaborations was observed. In Experiment 2, pictorial elaborations improved recall for both age groups. A significant Age x Encoding Condition interaction effect revealed that the benefit was especially pronounced for the older adults. the implications of these results for understanding the facilitative effects of pictorial illustrations on older adults. recall of verbal material are discussed.     

Individual differences in children's memory and reading comprehension: an investigation of semantic and inhibitory deficits

Three experiments compared the verbal memory skills of children with poor reading comprehension with that of same-age good comprehenders. The aims were to determine if semantic and/or inhibitory deficits explained comprehenders' problems on measures of verbal short-term memory and verbal working memory. In Experiment 1 there were no group differences on word- and number-based measures of short-term storage and no evidence that semantic knowledge mediated word recall. In Experiment 2 poor comprehenders were impaired on word- and number-based assessments of working memory, the greatest deficit found on the word-based task. Error analysis of both word-based tasks revealed that poor comprehenders were more likely to recall items that should have been inhibited than were good comprehenders. Experiment 3 extended this finding: Poor comprehenders were less able to inhibit information that was no longer relevant. Together, these findings suggest that individual differences in inhibitory processing influence the ability to regulate the contents of working memory, which may contribute to the differential memory performance of good and poor comprehenders.     

Processing resource capacity and the comprehension of garden path sentences

Three experiments explored the relationship between verbal working memory capacity and the comprehension of garden path sentences. In Experiment 1, subjects with high, medium, and low working memory spans made acceptability judgments about garden path and control sentences under whole sentence and rapid serial visual presentation (RSVP) conditions. There were no significant differences between subjects with different working memory spans in the comprehension of garden path sentences in either condition. In Experiments 2A and 2B, subjects with high and low working memory spans were tested on the same materials at three RSVP rates. There were no significant differences between subjects with different working memory spans in the magnitude of the effect of garden path sentences at any presentation rate. The results suggest that working memory capacity, as measured by the Daneman and Carpenter (1980) reading span task, is not a major determinant of individual differences in the processing of garden path sentences.     

Studies on responding under fixed-interval schedules of reinforcement: II. The scalloped pattern of the cumulative record

Responding under fixed-interval schedules usually generates either scalloped or break-and-run cumulative records. Earlier, it was generally accepted that the characteristic pattern was the scallop, but in recent years there has been an increasing emphasis on the break-and-run pattern. The break-and-run pattern has been shown quantitatively to provide a good fit of certain fixed-interval patterns. In the present work, responding during fixed-interval 1000-second components of a multiple fixed-interval 1000-second fixed-ratio 50 responses schedule was examined in two rhesus monkeys. Even after responding had started in an interval, there was a high tendency for responding to accelerate over subsequent 100-second segments of the interval. In segments with responding, the rate increased from one segment to the next in 303 of 389 segments in one monkey and in 310 of 419 segments in the other. The size of the increase was substantial, the rate in the fifth segment after responding started being an average of 4.5 times higher than the rate in the first segment after responding started. Hence, the usual pattern of responding in individual intervals was of sustained and substantial acceleration, vindicating numerically the conclusion derived from inspection of the scalloped patterns of the cumulative records.     

Skill in map reading and memory for maps

Studies of expertise have typically shown that experts have better memory for materials from their fields than do novices. However, previous research on memory for maps has not shown the expected effect of expertise. The present study differed from previous studies by using contour maps as well as planimetric maps. In Experiment 1 the expected superiority in memory performance was found for skilled map readers when contour maps were used, but not when planimetric maps were used.

In Experiment 2, the main results of Experiment 1 were replicated, and, in addition, process tracing data were obtained during both study and test phases of contour map learning. Objective measures of attentional and retrieval focussing revealed almost no differences between the skilled and unskilled subjects. However, analyses of verbal protocols showed that the skilled subjects made more use of specialist schemata, whereas the unskilled subjects spent more time in reading place names. During recall, the skilled subjects made more use of both specialist and “lay” schemata, whereas the unskilled retrieved more place-name information.

The results are interpreted in terms of a schema-based approach to expertise.