Choice, changeover, and travel: A quantitative model

Six pigeons were trained on concurrent variable-interval schedules in which responding on fixed-interval schedules was required to give access to the alternate schedule. Responding on the concurrent schedules was not allowed, after changing over had commenced, until the changeover schedule had been completed. In Parts 1 to 3 of the experiment, the changeover fixed-interval schedules were equal and were 0 s, 10 s, and 20 s, respectively. In each part, the relative frequency of reinforcement obtained on the concurrent schedules was varied over at least five conditions. In Part 4, the concurrent schedules were equal, and one changeover fixed-interval schedule was twice the other. Under these conditions, the absolute sizes of the changeover schedules were varied. Increasing the changeover requirement from 0 s to 10 s (Parts 1 and 2) resulted in increases in the sensitivity of behavior allocation to reinforcers obtained, but no further increase was obtained when the changeover schedules were increased to 20 s (Part 3). In Part 4, performance was biased towards the concurrent schedule that took less time to enter. These results are consistent with a subtractive punishment model of travel in which the degree of punishment is measured by the number of reinforcers apparently lost from a schedule when the subject changes to that schedule. Absolute times spent on the main keys could be accurately described by a previous model of changeover performance.     

Kindergarten attendance in relation to educational level and intelligence in adulthood: A geographical analysis

Level of school education and performance on an intelligence test were analysed for 32 557 Danish young adult males as a function of the geographical region in which they were reared. Positive associations were found between both educational levels and test scores on the one hand, and the proportion of infants attending kindergartens in the given regions (according to official statistics) on the other. Adults who were reared in regions where kindergarten attendance had been high tended to have higher educational levels and test scores, although the data do not permit a precise estimate of the magnitude of this effect. The relationship between kindergarten attendance and intelligence test score appears to have been mediated by educational level. Kindergarten attendance was more common in regions with high population density and high average incomes but the relationship of kindergarten attendance to educational level was significantly independent of these associations. These findings are consistent with the hypothesis that kindergarten attendance can have long-term educational benefits, and might therefore partially explain the upward trend in intelligence test scores over the last few decades.     

What is educational theory and how to make it?

An analysis is provided detailing the conditions for the appropriate theoretical study of the object of educational science: pedagogy.     

Choice, changeover, and travel

Since foraging in nature can be viewed as instrumental behavior, choice between sources of food, known as “patches,” can be viewed as choice between instrumental response alternatives. Whereas the travel required to change alternatives deters changeover in nature, the changeover delay (COD) usually deters changeover in the laboratory. In this experiment, pigeons were exposed to laboratory choice situations, concurrent variable-interval schedules, that were standard except for the introduction of a travel requirement for changeover. As the travel requirement increased, rate of changeover decreased and preference for a favored alternative strengthened. When the travel requirement was small, the relations between choice and relative reinforcement revealed the usual tendencies toward matching and undermatching. When the travel requirement was large, strong overmatching occurred. These results, together with those from experiments in which changeover was deterred by punishment or a fixed-ratio requirement, deviate from the matching law, even when a correction is made for cost of changeover. If one accepted an argument that the COD is analogous to travel, the results suggest that the norm in choice relations would be overmatching. This overmatching, however, might only be the sign of an underlying strategy approximating optimization.     

Choice and multiple reinforcers

Pigeons chose between equivalent two-component mixed and multiple terminal-link schedules of reinforcement in the concurrent-chains procedure. The pigeons preferred the multiple schedule over the mixed when the components of the compound schedules were differentiated in terms of density of reinforcement, but the pigeons were indifferent when the components were differentiated in terms of number of reinforcers per cycle. Taken together, these results indicate that a local variable, the interval to the first reinforcer, but not a molar variable, the number of reinforcers, was sufficient to differentiate the components and thereby evoke preference.     

THE FUNCTIONS OF ASSESSMENT: IMPLICATIONS FOR SELECTION AND DEVELOPMENT OF DEVICES FOR ASSESSING REPERTOIRES IN CLINICAL,EDUCATIONAL, AND OTHER SETTINGS

An attempt is made to identify the many different functions that assessment of an individual's repertoire can serve. Implications of these functions for the character of and evidence about assessment devices are suggested. The functions fall into two general groups, those which influence decisions regarding an individual learner, and those which influence policy, program development, and scientific knowledge. The first group of functions is presented in a rough chronological sequence such that they form a “behavioral assessment funnel,” beginning with functions involving broad-band assessment to identify likely persons and skill areas, and narrowing to the precise pinpointing, monitoring, and follow-up functions. The contribution of behavior analysis and behavior therapy to assessment methodology in this sequence is identified as well as the areas where more traditionally conceived methods are still useful. The second group of functions and behavioral contributions to it are then discussed.     

Effects of fixed-ratio sample and choice response requirements upon oddity matching

Three pigeons were trained on oddity matching in which either 1, 4, 8, 16, or 32 sample-key observing responses were required to turn off the sample stimuli and turn on the comparison stimuli. Oddity accuracy increased when the observing-response requirement was raised and decreased when the requirement was lowered. Next, while the observing requirement was maintained at one response, the number of responses required to the comparison stimuli was either 1, 4, 8, 16, or 32. Under these conditions, choice was defined as the comparison that first accumulated the required number of responses. In general, increasing the comparison-response requirement decreased accuracy and lowering the comparison requirement increased accuracy. The fixed-ratio observing requirements appeared to facilitate control by stimuli serving an instructional function.     

Duration and rate of reinforcement as determinants of concurrent responding

The duration and frequency of food presentation were varied in concurrent variable-interval variable-interval schedules of reinforcement. In the first experiment, in which pigeons were exposed to a succession of eight different schedules, neither relative duration nor relative frequency of reinforcement had as great an effect on response distribution as they have when they are manipulated separately. These results supported those previously reported by Todorov (1973) and Schneider (1973). In a second experiment, each of seven pigeons was exposed to only one concurrent schedule in which the frequency and/or duration of reinforcement differed on the two keys. Under these conditions, each pigeon's relative rate of response closely matched the relative total access to food that each schedule provided. This result suggests that previous failures to obtain matching may be due to factors such as an insufficient length of exposure to each schedule or to the pigeons' repeated exposure to different concurrent schedules.     

Choice, time allocation, and response rate during stimulus generalization

Six pigeons were trained to discriminate between two noise intensities using a procedure that assessed choice, time allocation, and response rate simultaneously and independently. Responses on the left or right key (R1 or R2) were respectively correct in the presence of two different intensities, S1 and S2. After a correct response, reinforcement became available for pecks on the center key. Reinforcement density for R1¦S1 relative to R2¦S2 was varied across experimental conditions. Generalization tests followed extensive training at each condition. As a function of stimulus intensity, proportions of initial choices of R2, of time spent in R2-initiated components, and of center-key responses emitted in R2-initiated components all yielded sigmoidal gradients of similar slope, which shifted slightly in location when relative reinforcement density changed. Changeovers were maximal where initial choice proportions approximated 0.5. Gradients relating the absolute number of center-key responses to stimulus intensity were also roughly sigmoidal, but were more sensitive to changes in reinforcement density. Gradients of momentary response rate also depended on reinforcement density. During training, large but transitory shifts in choice responding occurred when reinforcement density changed, while differences in momentary response rate developed slowly, suggesting separate control of choice and response rate by the contingencies of reinforcement.     

The effect of rearing environments on the contrafreeloading phenomenon in rats

Eight naive rats were reared in enriched or impoverished environments for 39 days after weaning and then lived in operant chambers, in which they could obtain food pellets freely or by lever pressing, for 25 or 30 days. The animals raised in an impoverished environment acquired the bar-press response quickly when placed in the operant chambers and maintained a preference for obtaining food via bar pressing. Animals raised in an enriched environment did not learn to lever press, as demonstrated by low levels of responding and the lack of bar pressing when free food was subsequently removed. It was concluded that restricting animals' postweaning environments facilitated learning in a choice situation, probably because of increased activity levels. The results are interpreted in relation to previous studies on rearing environments and on contrafreeloading.