THE EFFECTIVENESS OF A CONSTANT TIME-DELAY PROCEDURE TO TEACH CHAINED RESPONSES TO ADOLESCENTS WITH MENTAL RETARDATION

The effectiveness of a 5-s constant time-delay procedure to teach three chained food preparation behaviors to four moderately retarded adolescent students was evaluated within a multiple probe design across behaviors. Results indicate that the procedure was effective in teaching all four students to make a sandwich, boil a boil-in-bag item, and bake canned biscuits. The skills maintained with at least 85% accuracy over a 3-month period. Training generalized from the school to the home setting for the 2 subjects that completed generalization probe sessions. The percentage of errors across all skills and students was less than 9%.     

Test theory without an answer key

A general model is presented for homogeneous, dichotomous items when the answer key is not known a priori. The model is structurally related to the two-class latent structure model with the roles of respondents and items interchanged. For very small sets of respondents, iterative maximum likelihood estimates of the parameters can be obtained by existing methods. For other situations, new estimation methods are developed and assessed with Monte Carlo data. The answer key can be accurately reconstructed with relatively small sets of respondents. The model is useful when a researcher wants to study objectively the knowledge possessed by members of a culturally coherent group that the researcher is not a member of.This research was supported by NSF Grant No. SES-8320173 to the authors. We gratefully acknowledge comments and suggestions from John Boyd, Tarow Indow, and Kathy Maher as well as the editor and several anonymous referees.     

Latent trait models and dichotomization of graded responses

This paper discusses thecompatibility of the polychotomous Rasch model with dichotomization of the response continuum. It is argued that in the case of graded responses, the response categories presented to the subject are essentially an arbitrary polychotomization of the response continuum, ranging for example from total rejection or disagreement to total acceptance or agreement of an item or statement. Because of this arbitrariness, the measurement outcome should be independent of the specific polychotomization applied, for example, presenting a specific multicategory response format should not affect the measurement outcome. When such is the case, the original polychotomous model is called compatible with dichotomization.A distinction is made between polychotomization or dichotomization before the fact, that is, in constructing the response format, and polycho- or dichotomization after the fact, for example in dichotomizing existing graded response data.It is shown that, at least in case of dichotomization after-the-fact, the polychotomous Rasch model is not compatible with dichotomization, unless a rather special condition of the model parameters is met. Insofar as it may be argued that dichotomization before the fact is not essentially different from dichotomization after the fact, the value of the unidimensional polychotomous Rasch model is consequently questionable. The impact of our conclusion on related models is also discussed.     

A NOTE ON TRANSFER OF STIMULUS CONTROL IN THE DELAYED-CUE PROCEDURE: FACILITATION BY AN OVERT DIFFERENTIAL RESPONSE

This case study describes initially unsuccessful attempts to use the delayed-cue procedure to teach conditional discriminations to an individual with moderate mental retardation. The task was matching printed-word comparison stimuli to dictated-name sample stimuli. In three experiments, the subject typically waited for the delayed cue unless differential responses to the dictated samples (repeating the sample names) were required. Hence, the study provides an example of a way to make the delayed-cue method more effective. The stimulus control bases for the results are discussed.     

Predicting and scaling hens' preferences for topographically different responses

Six hens were exposed to several concurrent (second-order) variable-interval schedules in which the response requirements on the alternatives were varied. The response requirements were one key peck versus five key pecks, one key peck versus one door push, and five key pecks versus one door push. Response- and time-allocation ratios undermatched the obtained reinforcement ratios but were well described by the generalized matching law. Time and response bias estimates from two pairs of response requirements were used to predict bias in the third pairing. The predicted values were close to those obtained; this result supports the notion that both numerically and topographically different responses act as constant sources of bias within the generalized matching law. The differences between the response and time biases could be accounted for by the different times needed to complete each response requirement. The results also suggest that the door push is a useful operant for research with domestic hens.     

Essential independence and likelihood-based ability estimation for polytomous items

A definition ofessential independence is proposed for sequences of polytomous items. For items satisfying the reasonable assumption that the expected amount of credit awarded increases with examinee ability, we develop a theory ofessential unidimensionality which closely parallels that of Stout. Essentially unidimensional item sequences can be shown to have a unique (up to change-of-scale) dominant underlying trait, which can be consistently estimated by a monotone transformation of the sum of the item scores. In more general polytomous-response latent trait models (with or without ordered responses), anM-estimator based upon maximum likelihood may be shown to be consistent for under essentially unidimensional violations of local independence and a variety of monotonicity/identifiability conditions. A rigorous proof of this fact is given, and the standard error of the estimator is explored. These results suggest that ability estimation methods that rely on the summation form of the log likelihood under local independence should generally be robust under essential independence, but standard errors may vary greatly from what is usually expected, depending on the degree of departure from local independence. An index of departure from local independence is also proposed.This work was supported in part by Office of Naval Research Grant N00014-87-K-0277 and National Science Foundation Grant NSF-DMS-88-02556. The author is grateful to William F. Stout for many helpful comments, and to an anonymous reviewer for raising the questions addressed in section 2. A preliminary version of section 6 appeared in the author's Ph.D. thesis.     

Parental divorce as a factor in children''s perception of human relationships: An analysis of human movement responses in the Rorschach test

The subjects were 108 Swedish children between 10 and 12 years old, who constituted a divorce and a non-divorce group of 27 girls and 27 boys each. Rorschach Tests were administered individually and human movement responses were analysed. Non-divorce children perceived more cooperative and fewer hostile interactions than the divorce children. Responses containing figures engaged in hostile interaction were most common among divorce girls, whereas the divorce boys had difficulties in perceiving any interaction whatsoever. The different effect of parental divorce on the ability of girls and boys to develop satisfactory social relationships is discussed.     

NORMAL CHILDREN AS TUTORS TO TEACH SOCIAL RESPONSES TO WITHDRAWN MENTALLY RETARDED SCHOOLMATES: TRAINING,MAINTENANCE, AND GENERALIZATION

The findings of the three experiments reported herein indicate that normal children can successfully teach social responses (i.e., delayed imitation, cooperative play, and verbalization of positive comments) to withdrawn mentally retarded peers. The effects of the intervention generalized across stimulus and response conditions, while the trained and generalized levels of responding were maintained after the end of the intervention. Moreover, the subjects developed social responding within their classrooms and play areas parallel to the intervention and continued to increase such responding after the interruption of the intervention. Direct edible reinforcement appeared to be necessary at least during the initial period of the intervention. Vicarious edible reinforcement seemed useful to prompt the appearance of responding. Vicarious social reinforcement was ineffective at the beginning of the intervention, but apparently acquired prompting power at a later stage of training. Generalization results indicated that the similarity between the response occasions used for training and those used for testing generalization played an important role. Yet, the extensiveness of training and the development of responding within the classrooms and play areas may also have had a relevant effect. The development of social responding within the classrooms and play areas appeared to be mainly the effect of new learning. This was perhaps due to vicarious and direct social reinforcement.     

Changes in a multiple-response repertoire during response-contingent punishment and response restriction: Sequential relationships

A multiple-response baseline of four activities was established using gerbils as subjects. When one of the baseline responses was punished (Experiment 1) or restricted (Experiments 2 and 3), only the most probable of the alternative baseline responses increased. The response most likely to follow the punished or restricted responses during baseline sessions was also suppressed during subsequent punishment or response-restriction treatment.     

ANALYSIS OF THE CONSISTENCY OF OBJECTIVE MEASURES OF SEXUAL AROUSAL IN WOMEN

Eight adult women volunteers viewed the same erotic film in two different sessions. Their resulting genital responses were recorded simultaneously by three different measures: vaginal pressure pulse, vaginal blood volume, and labial temperature change. During the erotic stimulation, the vaginal pressure pulse and labial responses always increased, and the vaginal blood volume response increased on all but two occasions. Although there was considerable intersubject variability in each genital measure, all three measures were found to have some intrasubject consistency over sessions with respect to either their response amplitudes or patterns, with labial temperature being the most consistent on both parameters. The relationship between the response patterns of the three measures during the film was also relatively consistent across sessions, as was the correspondence between subjective ratings of arousal and both vaginal pressure pulse and labial responses but not vaginal blood volume response. To overcome the problem of considerable intrasubject variability of response amplitudes, it was suggested that the inclusion in the data analysis of several parameters of response patterns, which were relatively stable over sessions, might facilitate the evaluation of a treatment.