Glyn V. Thomas

Learning when reward is delayed: a marking hypothesis.

Rats were trained on spatial discriminations in which reward was delayed for 1 min. Experiment 1 tested Letts hypothesis that responses made in the home cage during the delay interval are less likely to interfere with learning than responses made in the maze. Experimental subjects were transferred to their home cages during the delay interval, and control subjects were picked up but then immediately replaced in the maze. Contrary to Letts hypothesis, both groups learned. Further experiments suggested that handling following a choice response was the crucial variable in producing learning: No learning occurred when handling was delayed (Experiment 2) or omitted (Experiment 3). One possible explanation for the fact that handling facilitated learning is that it served to mark the preceding choice response in memory so that subjects were then more likely to recall it when subsequently reinforced. In accordance with this interpretation, learning was found to be just as strong when the choice response was followed by an intense light or noise as by handling (Experiment 4). The implication of marking for other phenomena such as avoidance, quasi-reinforcement, and the paradoxical effects of punishment is also discussed.

Core beliefs in anorexic and bulimic women.

There is research evidence to suggest the presence of dysfunctional cognitions in anorexia nervosa and bulimia nervosa that are not related to food, weight, or shape. These maladaptive cognitions have not been addressed by the conventional cognitive behavioral models of etiology or therapy. This study aimed to assess the impact of unhealthy core beliefs on eating disorders and their symptoms. Twenty restricting anorexics, 10 bulimic anorexics, 27 bulimics, and 23 normal controls completed Youngs Schema Questionnaire. Eating behaviors and attitudes were also measured. The results indicate that both anorexic and bulimic women had significantly higher levels of unhealthy core beliefs than comparison women, but the clinical groups only differed on one individual core belief (entitlement). However, there were different patterns of association between core beliefs and eating psychopathology in anorexic and bulimic women. It is suggested that future clinical practice should incorporate core beliefs as a potential element in the assessment and treatment of eating disorders.

The relationship between parental bonding and core beliefs in anorexic and bulimic women

OBJECTIVE The role of core beliefs in the psychopathology of eating disorders has been considered in recent years. Young (1994) hypothesized that unhealthy core beliefs originate from the experience from the first few years of life. The aim of the present study was to consider whether perceived parental bonding might explain the development of such beliefs in eating disordered women. METHOD The participants were 30 anorexics, 27 bulimics and 23 comparison women who completed measures of core beliefs and perceived parental bonding. RESULTS There were significant differences in perceived parental bonding behaviours across groups. The association between parental bonding and core beliefs were much stronger in the anorexic group than that in either the bulimic or the control group. In particular, a perceived low level of parental care was predictive of the presence of some unhealthy core beliefs in anorexic women. CONCLUSION Longitudinal research is needed to confirm these findings among anorexic and bulimic women. Clinically, these findings provide insight into the possible origins or core beliefs, and hence might aid their challenge in schema-focused cognitive therapy.

The writing strategies of graduate research students in the social sciences

SummaryA 35-item questionnaire concerning writing habits, experiences of writing and productivity was sent to 228 full-time, U.K. domiciled, social science research students. One hundred and one complete responses were received. Cluster analysis was used to identify three distinct groups of students in terms of the strategies they used when writing: “Planners”, who planned extensively and then made few revisions, “Revisers”, who developed content and structure through extensive revision, and “Mixed Strategy” writers, who both planned before starting to write and revised extensively as part of their writing processes. The Planners reponed higher productivity than both the Revisers and Mixed Strategy Writers. Planners and Revisers did not differ significantly in how difficult they found writing to be; Planners found writing less difficult than did the Mixed Strategy Writers. We conclude that working from a plan can be an effective writing strategy for some, but that planning is neither a necessary nor a sufficient condition for writing success.

Contiguity and contingency in instrumental conditioning

Abstract There have been several attempts to construct molar theories of conditioning on the empirical basis that response-reinforcement contingency is important in determining conditioning. Such theories claim to explain behavior in terms of molar level processes which transcend the molecular level and, therefore, are not reducible to molecular processes or their interaction. These molar theories are critically examined and found to be seriously flawed because they fail to account for the effects of delaying reinforcement (degree of contiguity). Observed molar level relations, such as the matching law, do not require a molar theory, but may be more usefully considered as a product of molecular processes.

Is reported childhood sexual abuse associated with the psychopathological characteristics of patients who experience auditory hallucinations

OBJECTIVE The aim of this study was to determine whether reported childhood sexual abuse is related to the severity of symptoms in patients who experience auditory hallucinations. METHOD A sample of 26 adult male and females with psychotic disorders involving auditory hallucinations were interviewed and were asked to complete three self-report measures: the Dissociative Experiences Scale (DES-II and DES-taxon versions); the Beck Depression Inventory (BDI); and the Beliefs About Voices Questionnaire (BAVQ). They were also asked about any history of sexual abuse in childhood. RESULTS A history of childhood sexual abuse was reported by 10 of the 26 patients (38.5%), and was associated with higher levels of depression and dissociation, as well as being linked to a tendency to regard the voices as more malevolent. The same three features were all associated with the age at first reported abuse, with a younger age of first experience being related to higher levels of psychopathology in all instances. CONCLUSIONS These results require replication and refinement in future research, but indicate a need for greater attention to be paid to the possible role of childhood sexual abuse when understanding and treating auditory hallucinations.

Origins of fear of dogs in adults and children: the role of conditioning processes and prior familiarity with dogs.

One hundred adults and 30 children completed questionnaires to investigate fear of dogs. Dog fearful adults asked to recall the origins of their fear reported classical conditioning experiences more frequently than vicarious acquisition or informational transmission. Overall, however, there was no difference in the frequency of attacks reported by the fearful and non-fearful groups. Significantly more fearful than non-fearful adults reported little contact with dogs prior to the onset of their fear which suggests that early non-eventful exposure to dogs may prevent a conditioning event from producing a dog phobia. Most adults reported that their fear began in childhood, and dog fear were more frequently reported by children than by adults. In the aggregate, however, dog-fearful adults and children differed in several ways; children were more likely than adults to report having received warnings about dogs, but also to recognize the potential attractiveness of a friendly dog. Unlike dog-fearful children, dog-fearful adults reported many other fears in addition to their fear of dogs. A better understanding of fear of dogs in adults may depend on discovering why some dog-fearful children, but not others, apparently lose their fear of dogs as they become older.

Outcome of group cognitive-behavior therapy for bulimia nervosa : the role of core beliefs

It is hypothesized that individuals who benefit less from CBT will be those who have more pathological core beliefs (unconditional beliefs, unrelated to food, shape and weight). Twenty bulimic women were treated using 12 sessions of conventional group CBT. Eating behavior and attitudes were assessed pre- and posttreatment. Core beliefs were assessed at the beginning of the programme, and were used as predictors of change across treatment (once any effect of pretreatment psychopathology was taken into account). Group CBT was effective, with reductions of over 50% in bulimic symptoms. Outcome on most indices was associated with pretreatment levels of pathological core beliefs. Possible reasons for these findings are discussed.

Individual differences in the writing behaviour of undergraduate students

Background. Writing is an important skill required in all graduate employment but we lack information on the most effective ways to write, and how to foster writing expertise in students. It is widely held that writers evolve characteristic patterns of working (strategies), and that these strategies are important for writing success and efficiency. Most of the available data on the writing strategies of expert writers, however, consist of questionnaire responses produced some time after writing itself, and it would be helpful to have more direct information on writing strategies and their effects. Aims. To establish whether student writers develop stable writing strategies, and to examine the relation, if any, between writing strategy and writing success. Sample. Twenty-five first year undergraduate students studying for a degree in psychology. Methods. Records of their writing activities were completed by students concurrently with writing each of two essays (term papers). Results. Analysis of the records identified patterns of working which differed across individuals. Nearly three-quarters of the students displayed the same pattern of writing behaviour (strategy) for both their essays. The strategies identified from the activity records were broadly consistent with the descriptions of writing behaviour derived from previous questionnaire studies. There was, however, no significant association between writing strategy and essay mark. Conclusion. Many students evolve stable writing strategies, which may differ across students. Most of these strategies seem adequately effective in terms of producing course essays. Consequently, unless a student complains of writing difficulties, then tolerance of a range of approaches may be desirable in writing instruction.

The role of marking when reward is delayed.

Two-choice spatial discrimination by rats is enhanced if a salient stimulus marker occurs immediately after every choice response and again after a delay interval (Lieberman, McIntosh & Thomas, 1979). Three experiments further explore this effect. Experiment 1 found that the second marker is unnecessary. Experiment 2 found that a marker presented before a response is as effective as one presented after. Both effects could be explained in terms of markers focusing attention on subsequent cues. Experiment 3, however, found that markers after choice enhance learning even when no discriminative cues are present following the marker. Markers thus appear to initiate both a backward search through memory and attention to subsequent events; both processes help to identify events that might be related to the unexpected marking stimulus.