Towards an account of argumentation in science

In this article it is argued that a complex model that includes Toulmin's functional account of argument, the pragma-dialectical stage analysis of argumentation offered by the Amsterdam School, and criteria developed in critical thinking theory, can be used to account for the normativity and field-dependence of argumentation in science. A pragma-dialectical interpretation of the four main elements of Toulmin's model, and a revised account of the double role of warrants, illuminates the domain specificity of scientific argumentation and the restrictions to which the confrontation and opening stages of scientific critical discussions are subjected. In regard to the argumentation stage, examples are given to show that a general account of argumentation, as advocated by informal logicians, is not applicable to arguments in science. Furthermore, although patterns of inference differ in various scientific practices, deductive validity is argued to be a crucial notion in the assessment of scientific arguments. Finally, some remarks are made concerning the burden of proof and the concluding stage of scientific argumentation.     

Assessing control by elements of complex stimuli in delayed matching to sample.

A series of six experiments examined delayed identity matching-to-sample performances of subjects with mental retardation. The stimuli were either one or two simultaneously displayed forms. When the reinforcement contingencies required that only one form exert discriminative control, all subjects achieved high accuracy scores. However, accuracy scores were substantially lower when the contingencies required discriminative control by two forms, suggesting restricted stimulus control. The decline in matching accuracy appeared to reflect selective losses of conditional control by sample stimuli and shifts in control to features of the comparison stimulus displays. The experiments suggest improved techniques for assessing control by complex stimuli and for evaluating the effects of procedures that seek to broaden restricted stimulus control. The results challenge interpretations based on stimulus-generalization decrement or shared attention.     

PARENT EDUCATION PROJECT III: INCREASING AFFECTION AND RESPONSIVITY IN DEVELOPMENTALLY HANDICAPPED MOTHERS: COMPONENT ANALYSIS,GENERALIZATION, AND EFFECTS ON CHILD LANGUAGE

We evaluated the effects of a parent training program consisting of verbal instruction, modeling, and feedback on the affection and responsivity of 3 developmentally handicapped mothers towards their children. The results indicated the following: First, the training package increased maternal physical affection, praise, and imitation of child vocalizations. These parenting skills increased to levels found in comparison groups of nonhandicapped mothers. Second, the training package was more effective than verbal instruction alone, the latter being the predominant method presently used by social service workers. Third, most maternal gains were maintained over a 3- to 18-month follow-up period, although one mother required a reinforced maintenance procedure. Fourth, instructing mothers to generalize served to increase the generalization of newly acquired skills from play times (the training context) to child-care tasks (e.g., diapering, feeding). Fifth, teaching the parents to imitate child vocalizations was related to gains in both the frequency and quality of verbal behavior of the two language delayed children as measured by standardized developmental tests and in vivo comparisons with age-matched children (who had nonhandicapped parents). These results show that behavioral instruction can improve important child-rearing skills of developmentally handicapped mothers, with corresponding benefits to their children.     

EVALUATION OF THE GENERALIZED EFFECTS OF A PEER-TRAINING PROCEDURE WITH MODERATELY RETARDED ADOLESCENTS

The use of peer-training procedures by moderately mentally retarded adolescents was evaluated in two experiments. In Experiment 1, 2 students received instruction on peer-training skills to teach a vocational task to 7 classmates. Following instruction, both peer trainers were successful in teaching their classmates to perform the target task and a second untrained (generalization) task. In Experiment 2, 1 peer trainer taught 3 peers to use picture prompts to complete one or two complex vocational tasks. Following instruction by the peer trainer, the trainees independently used novel pictures on novel tasks. The results of both experiments indicate that peer training with moderately handicapped students can be an effective instructional procedure, with generalization occurring for both the trainers (Experiment 1) and the trainees (Experiment 2).     

FACILITATING GENERALIZED REQUESTING BEHAVIOR IN BROCA'S APHASIA: AN EXPERIMENTAL ANALYSIS OF A GENERALIZATION TRAINING PROCEDURE

The effects of a generalization training procedure on requesting by 4 subjects with chronic Broca's aphasia were examined using a multiple baseline design across behaviors and subjects. Subjects were trained to request information on three topics sequentially. Generalization across topics and persons was assessed in weekly probe sessions consisting of 5-min conversational interactions with trainers and unfamiliar volunteers in a nontreatment setting. Results revealed generalization effects were greatest when trainers, as opposed to unfamiliar volunteers, served as conversational participants. Nevertheless, subjects' requests increased with all conversational participants to a level comparable to a normal comparison group assessed under conditions identical to the experimental probes. Social validation of treatment effects using a subjective evaluation procedure revealed significant improvement on the parameters of talkativeness, inquisitiveness, and conversational success.     

Secondary generalization and categorization in pigeons

In Experiment 1, one group of pigeons learned to classify a set of stimuli into the human language classes cat, flower, car, and chair (categorization); another group learned to classify the same set into arbitrary classes (pseudocategorization). Then, both groups were trained on a new categorization task and their performance compared to that of a control group that had no initial classification training. Hull's (1943) notion of secondary generalization (generalization that is not based on physical similarity but on mediating associations) predicts that categorization experience will facilitate the learning of a new categorization task, whereas pseudocategorization experience will impair it. However, in Experiment 1, performance on the new categorization task was not differently affected by prior experience. In Experiment 2, pigeons initially trained to classify a set of 48 stimuli (original training) were later trained to classify a subset of four of these stimuli using new responses (reassignment training). Then, they were tested on the 44 remaining stimuli. Performance better accorded with original than with reassignment training, indicating that categorization training did not lead to the formation of equivalence classes of stimuli, in which the equivalence relationship is mediated by secondary generalization. The lack of evidence of secondary generalization implies that our pigeons failed to meet Lea's (1984) criterion for conceptual behavior.     

Discrete and continuous measures of dimensional stimulus control

In two sets of experiments, we examined dimensional stimulus control of pigeons' responses to a visual flicker-rate continuum. In the first experiment, responses to a single key were reinforced periodically during stimuli from one half of the stimulus continuum, and responses during other stimuli were extinguished. In the second experiment, two response keys were simultaneously available, with reinforcement for each response alternative associated with different halves of the stimulus continuum. Conditions of the second experiment involved either free-operant or discrete-trial stimulus presentations. Results from these experiments show that positive dimensional contrast appeared in discrimination tasks with one or two response alternatives, but only with free-operant procedures. In addition, discrimination between stimulus classes established by differential reinforcement was assessed as accurately by continuous rate measures as by discrete response choice in the two-alternative situation. The general implication of these experiments is that response rate measures, when properly applied, may reveal sources of variation within stimulus classes, such as dimensional contrast, that are not evident with discrete measures.     

Instance‐based Learning: A General Model of Repeated Binary Choice

A common practice in cognitive modeling is to develop new models specific to each particular task. We question this approach and draw on an existing theory, instance‐based learning theory (IBLT), to explain learning behavior in three different choice tasks. The same instance‐based learning model generalizes accurately to choices in a repeated binary choice task, in a probability learning task, and in a repeated binary choice task within a changing environment. We assert that, although the three tasks are different, the source of learning is equivalent and therefore, the cognitive process elicited should be captured by one single model. This evidence supports previous findings that instance‐based learning is a robust learning process that is triggered in a wide range of tasks from the simple repeated choice tasks to the most dynamic decision making tasks. Copyright © 2010 John Wiley & Sons, Ltd.