Autocorrelation of choice-reaction times.

A choice-reaction (CR) task requires that the subject estimate, raking the warning signal or his response on the preceding trial as a reference point, the time when the reaction stimulus is due, so that he can begin deciding on his response at an appropriate time. This paper presents a model for the reproduction of temporal intervals, with particular emphasis on the sequential statistics of a series of such reproductions. When this model is concatenated with the sequential probability ratio test model for 2CRT, it provides a quantitative account of the pattern of autocorrelation found in a series of RTs. There is no corresponding autocorrelation in the incidence of errors, however, because after an error the subject systematically adjusts the epoch at which he begins sampling as a precaution against a further error. These post-error adjustments can readily be incorporated into the model. The ideas presented enable several different CR phenomena to be related, and they have implications for the relation between speed and accuracy, for the form of empirical distributions of RTs, and for the effects of temporal uncertainty.     

A critical comparison of two random-walk models for two-choice reaction time

Two random-walk models for two-choice reaction time, being the sequential probability ratio test model initially suggested by Stone and the relative judgment theory recently proposed by Link, are here compared. The comparison shows the precise mathematical relation between the models, the predictions they have in common, and two points at which they differ. Three experiments concerned with the effect of stimulus probability on two-choice reaction time are examined with respect to three predictions from the models. In this three-way comparison the two models are more like each other than either is to the data; a greater variety of phenomena is revealed than either model can at present accommodate.     

Language comprehension in old age

Three experiments examined the effects of aging on comprehension of spoken language. Integrative and constructive aspects of comprehension showed much more marked age-related deficits than registration of surface meaning. Experiment 1 showed that old subjects had difficulty in making inferences based on presented facts. Experiment 2 revealed a similar deficit in old people's ability to detect anomalies in newly presented information by reference to prior everyday knowledge. And Experiment 3, which tested story recall, showed that old subjects were less well able to extract and retain gist information than younger subjects. These difficulties are interpreted as reflecting a limitation in processing capacity such that the demands of concurrently registering surface meaning and simultaneously carrying out integrative and constructive processes exceed capacity in old age.     

THE EFFECTS OF KNOWN-ITEM INTERSPERSAL ON ACQUISITION AND RETENTION OF SPELLING AND SIGHTREADING WORDS1

The use of well-documented procedures such as shaping, differential reinforcement, and fading may not be the most practical for teaching certain academic behaviors. An alternative procedure of interspersing trials on previously trained items with trials on unknown items has been suggested, but its effects on acquisition and retention have not been systematically examined. This study investigated the effects of interspersing known items during training on new tasks. Six mentally retarded adolescents were given pretests on spelling and sightreading words, which were divided into pools of learned and unlearned items. Training and baseline conditions were implemented concurrently, using a multi-element design. During interspersal training sessions, 10 known words from the pretest were alternately presented with each of 10 test words that were incorrect on the pretest. The ratio of previously mastered words to test words was gradually reduced. During baseline sessions, 10 different test words were presented without alternation of previously known words. During this condition, a procedure involving high-density social reinforcement contingent on task-related behaviors, but not necessarily correct responses, was later introduced, followed by a return to the original noninterspersal baseline. During all conditions, test words were deleted and replaced after meeting a mastery criterion of three consecutive correct trials. Retention tests were administered over learned test words for all conditions, at specified intervals. Results showed that both acquisition and retention of spelling and sightreading words were facilitated by the interspersal procedure. All subjects acquired more words during the interspersal condition than either the high-density or baseline conditions. The effectiveness of the procedure may possibly be attributed to better maintenance of attending behavior to unknown items as a function of the inclusion of known items, which directly increase the amount of reinforcement for correct responses during the early stages of skill acquisition.     

An experimental analysis of electricity conservation procedures

Daily electricity consumption of four families was recorded for 106 days. A reversal design, consisting of various experimental conditions interspersed between repeated baseline conditions, was used. During experimental conditions, daily prompts (written conservation slogans attached to front doors) and/or daily feedback (daily kilowatts consumed and daily cost information) were in effect. Maximum consumption occurred during the initial baseline; minimum consumption occurred during different experimental conditions for different families. The mean decrease from the maximum to the minimum for all families was 35%. Reversals in consumption were demonstrated in three families, although successive baselines tended to decrease. No clear differences in effectiveness between prompting and feedback conditions were apparent. The procedures used resulted in considerable dollar savings for the families.     

THE CHANGING CRITERION DESIGN

This article describes and illustrates with two case studies a relatively novel form of the multiple-baseline design called the changing criterion design. It also presents the design's formal requirements, and suggests target behaviors and circumstances for which the design might be useful.     

Autonomous processes in comprehension: A reply to Marslen-Wilson and Tyler

A criterion which has been proposed for distinguishing minds from computing systems is examined from the point of view of some current work on computer induction.     

Inferential reasoning in old age

Two experiments examined the effects of aging on the kind of inferential reasoning required in comprehending discourse. In Experiment 1 old subjects made more errors than young subjects in solving logical problems framed in everyday language. Unlike the young subjects they had more difficulty when the problems were spoken than when they were written. Experiment 2 revealed that old subjects are inefficient at extracting implicit information during reading; they fail to generate bridging inferences to supply missing information, so that comprehension is restricted to explicitly stated information. The results show that verbal reasoning ability is impaired in old age and that this affects language comprehension in both listening and reading although the deficit is more marked in listening.     

A comparison of three interventions for increasing oral reading performance: Application of the instructional hierarchy

The instructional hierarchy is a behavior-analytic model that links level of academic skill development (i.e., acquisition, fluency, generalization, adaptation) with appropriate instructional techniques. The present study used the instructional hierarchy to compare the effects of three instructional interventions (listening passage preview, subject passage preview, and taped words) on subjects' oral reading performance on word lists and passages. Subjects were 4 male students with learning disabilities who ranged in age from 8 years 10 months to 11 years 11 months. A multielement design was used to compare the effects of the three interventions to each other and to baseline. Results indicated that the listening passage preview intervention (which contained modeling, drill, and generalization components) produced the largest performance gains. The implications of these results for selecting academic interventions based on the instructional hierarchy are discussed.     

Designing a behavioral program for a barrio in Tegucigalpa, Honduras

Health in Housing initiated a behavioral program of education and skills training for children and adults in a community of 30,000 persons living in substandard conditions in Tegucigalpa, Honduras. To measure achievement in the long-range project, 21 families of Flor del Campo participated in a preliminary three-part survey of their (a) health, (b) housing and the environment, and (c) family history. Doctors, designers, and educators worked with Honduran personnel in the first survey. Following functional analyses of the home and surrounding environment and the physical status of the individuals living there, procedures provide the family with treatment and training for home and environment improvement. Graphic, verbal, and numerical data, incorporated into a master computerized system, record events of each family member: training programs experienced, health care delivery courses taken, medical treatments, growth of children, literacy changes, educational courses completed, kinds and amounts of foods eaten, household and building materials purchased. Ongoing functional analysis and a long-range evaluation are made of the progress of each participating individual in a family. Teams revisit each house to observe and record any changes in the physical and environmental facility and the health and life-styles, and to report any indications of new health problems or recurrences.