Defining Trauma: Terminology and Generic Stressor Dimensions1

The present report discusses vague and/ or confusing terminology that is employed in research and clinical work in the area of “traumatic stress”. It divides the stress process into three major aspects and suggests appropriate terminology for each aspect, focusing on the input, or stressor, aspect. Eight generic stressor dimensions are suggested that cut across different types of traumatic events, along with research supporting the association of these dimensions with stress responses. Recommendations are made for future research directions.     

Development of conditional and equivalence relations without differential consequences

Two experiments were conducted to establish conditional stimulus relations without differential consequences and to test for the emergence of other relations. In Experiment 1, 3 adults responded to match-to-sample displays in which sample-comparison pairs were constant while the second comparison presented with each pair changed periodically across trials. No differential consequences followed any comparison selections. All subjects learned conditional relations between constant samples and comparisons, but results of tests for transitivity in those relations were equivocal. In Experiment 2, 4 children were given unreinforced training and testing similar to that provided to the adults in Experiment 1, with procedural refinements. One child learned conditional relations and demonstrated emergent relations that confirmed the development of two four-member equivalence classes. Another child learned the conditional relations but did not demonstrate any emergent relations reliably. A 3rd child, after reinforced training on two conditional relations, learned four new conditional relations without differential consequences and demonstrated symmetry but not equivalence in the trained relations. The 4th child did not learn the conditional relations. These findings emphasize the importance of careful construction of tests for stimulus equivalence and suggest a need for critical analyses of the apparent emergence of untrained stimulus relations on unreinforced tests that has been observed in several stimulus equivalence studies.     

Short-term and long-term effects of reinforcers on choice

The relation between molar and molecular aspects of time allocation was studied in pigeons on concurrent variable-time variable-time schedules of reinforcement. Fifteen-minute reinforcer-free periods were inserted in the middle of every third session. Generalized molar matching of time ratios to reinforcer ratios was observed during concurrent reinforcement. Contrary to melioration theory, preference was unchanged during the reinforcer-free periods as well as in extinction. In addition to this long-term effect of reinforcement, short-term effects were observed: Reinforcers increased the duration of the stays during which they were delivered but had little consistent effect either on the immediately following stay in the same schedule or on the immediately following stay in the alternative schedule. Thus, an orderly effect of reinforcer delivery on molecular aspects of time allocation was observed, but because of its short-term nature, this effect cannot account for the matching observed at the molar level.     

On the existence of independent explicit and implicit learning systems: An examination of some evidence

Hayes and Broadbent (1988), among others, have proposed that there are two independent systems of learning in humans. In their theory, they postulate that theexplicit learning system gives rise to knowledge that is verbally describable, whereas theimplicit learning system deals with knowledge that is not amenable to verbal report. Hayes and Broadbent presented data that they claimed supports a distinction between these two systems of learning. Their experiments involved the performance of subjects on two superficially similar tasks, and their claim was that one of the tasks induced learning in the explicit system, and the other induced learning in the implicit system. However, in five experiments here, we failed to find any convincing support for their empirical or theoretical claims. Our results suggest that the two tasks do not differ by inducing different types of learning, but simply differ in their degree of difficulty.     

Assessing violent offending in serious juvenile offenders

The convergent validity of the two most frequently used methods for assessing violent offending in juveniles (i.e., selfreports and arrests) was evaluated. Participants were 87 serious juvenile offenders and their maternal figures, primarily from disadvantaged families. Validation measures tapped established behavioral, family, and peer correlates of delinquency. Results failed to support the ability of either arrests for violent crimes or selfreported violent offenses to index violent criminal behavior accurately. Several methodological features of the study support our hypothesis that the findings were not spurious. Procedural and conceptual implications of the findings are discussed.The Family and Neighborhood Services Project was funded by Grant 2H87MH43557-04 to the South Carolina Department of Mental Health from the National Institute of Mental Health. The authors extend their most sincere appreciation to Commissioner Joseph Bevilacqua, Commissioner Richard McLawhorn, Joe James, Dale Chandler, Madeline Blackwell, Kristen Rowden, Pam King, Nancy King, Nancy Yue, and Jerry DeLoye.     

Graduate psychology students' perceptions of the scientist-practitioner model of training

Since its inception over forty years ago, there has been considerable controversy regarding the viability of the scientist-practitioner model for training professional psychologists. The present study utilized a combination of qualitative and quantitative research methods to assess graduate psychology students' (n=24) perceptions of this training model. Counselling, clinical, and school psychology students participated in semi-structured interviews and were administered the Vocational Preference Inventory, Form B (Holland, 1977) and the Scientist-Practitioner Inventory (Leong & Zachar, 1991). Data were analyzed using a combination of grounded theory (Glaser & Strauss, 1967) and additional qualitative data analytic approaches (Miles & Huberman, 1984). A number of patterns were observed between students' perceptions and feelings about the scientist-practitioner model and their definition of science, career interests, and shaping experiences. Implications for the future training of professional psychologists are discussed.     

Preparing direct service staff to teach people with severe disabilities: A comprehensive evalution of an effective and acceptable training program

In light of the continuing need for residential, direct service staff to be able to teach people with severe disabilities, we comprehensively evaluated a program to train staff in behavioral teaching strategies. The program was developed and evaluated with attention given to recent concerns in the staff management literature regarding shortcomings with staff training research. The training program, involving a maximum of four, 2-hr classroom instruction sessions and three in vivo observation and feedback sessions, was evaluated in four studies. In Study 1, the program was shown to improve verbal skills of 13 direct service staff regarding behavioral teaching principles and terminology. In Study 2, the program was demonstrated to improve performance based teaching skills of nine staff and four staff supervisors. In Study 3, the program was shown to result in improvements in adaptive skills of three clients with severe disabilities when direct care staff used their newly acquired teaching skills with the clients. In Study 4, the training program was shown to be well received among 17 staff trainees, although the trainees were more accepting of some program components than others. Results of the studies are discussed in regard to the importance of agencies providing effective and acceptable staff training programs. Future research areas also are noted, focusing on the need to determine, and minimize where possible, the amount of time required to conduct successful staff training.     

Color correspondence in apparent motion

To maintain figural identity during motion perception, the visual system must match images over space and time. Correct matching requires a metric for identifying "corresponding" images, those representing the same physical object. To test whether matching is based on achromatic (black/white) polarity and chromatic (red/green) color, observers viewed an ambiguous motion display and judged the path of apparent motion. Matching preserved black/white identity regardless of whether frames were viewed binocularly or dichoptically. Red/green identity was also preserved, but coherence of motion depended in part on the number of frames in the motion sequence and on the background luminance. These results suggest that correspondence is computed by a weighted metric containing terms for image features coded early in visual processing.