Group Learning Curves: The Effects of Turnover and Task Complexity on Group Performance1

This study examined the effects of turnover and task complexity on group performance. Two hundred and forty subjects arranged into three-person groups performed a production-type task for six experimental periods. The design was a 2 (Turnover vs. No Turnover) × 2 (Simple vs. Complex Task) × 2 (Male vs. Female) × 6 (Periods) factorial with repeated measures on the last factor. The analysis revealed that group performance improved markedly as groups gained experience with the task. Groups which did not experience turnover (closed groups) produced significantly more products than did groups which experienced turnover (open groups). The superior performance of closed over open groups was amplified over periods. Groups produced more of the simple than of the complex product, and this difference was also amplified over periods. The gap in the performance of closed versus open groups increased over periods, and the increase in the gap was greater for the simple than for the complex task. The lesser impact of turnover on the complex task is consistent with an innovation hypothesis, according to which increases in the production of complex tasks are due more to innovation than to repetition. Supportive analyses of innovation data are reported.     

Coping with intractable controversies: The case for problem structuring in policy design and analysis

Intractable controversies and other types of policy disagreements correspond to policy problems with a different structure. The more structured a problem is, the more consensus there is about which values and information are at stake in the process of problem solving. Policymakers like to treat problems in as structured a way as possible. Three policy strategies are described to move away from the unstructured to the more structured problem type. However, policymakers run the risk of oversimplifying an ill-structured problem, which means that elements of the problem situation relevant to other actors are overlooked or denied. Hence, policy controversies may become intractable. The remedy is a fourth strategy, characterised by problem structuring. This strategy requires political participation of actors with different views on the problem, and an argued political problem choice. His main research areas are problem structuring in public policy, knowledge use, environmental risk, technology and democracy. He is currently working on knowledge-based policy strategies for addressing the issue of climate change. His research interest is to develop and apply discursive and/or argumentative approaches to the policy process.     

Roles of Visual Information for Control of Reaching Movements in Children

What visual information do children normally require for the control of reaching movements? How is performance affected when children do not have access to the preferred mode of perceptual information? These questions were studied in 28 children who were tested on 3 occasions: at 6, 7, and 8 years of age. The task was to pick beads, 1 at a time, from 1 cup and carry them to another cup. With the aid of a mirror arrangement and a curtain, the amount of visual information was manipulated with regard to both the target and the performing hand. The movements were monitored with an optoelectronic device (SELSPOT II) and analyzed in terms of transport and object-handling phases. Results showed that object handling required visual information on both hand and target. For the transport phase of the movement, visual information on the spatial location of the target was sufficient, and sight of the hand did not improve performance. In contrast to adult subjects, when children did not have access to the required visual information, their performances deteriorated markedly. These results indicate that from the age of 6, children use visual information for control of arm movements in a manner like that of adults, although with less accuracy and speed. However, even 8-year-old children are limited in their ability to use alternative perceptual strategies for movement control, and they therefore become less flexible and more dependent on visual information.     

Irrational Beliefs, Interpersonal Perception and Marital Adjustment

To test the hypothesis that the major evaluative beliefs postulated by Rational-Emotive Behaviour Therapy are related to marital adjustment, 50 married couples completed the Dyadic Adjustment Scale (DAS) and the Survey of Personal Beliefs (SPB). Significant correlations were found between DAS scores and three subscales (Other directed shoulds, Low frustration tolerance and Self worth) of the SPB. On the interpersonal dimension of assumed similarity, females in the high dyadic adjustment group were better able to predict their spouses' awfulizing, low frustration tolerance and self-worth beliefs than were females in the low adjustment group. However, the present study offers only limited support for the hypothesis that interpersonal perception of irrational evaluative beliefs is related to marital adjustment.     

Spontaneous Imitation of Fundamental Frequency and Speech Rate by Nonstutterers and Stutterers

Speech can be described either in terms of acoustics, as a perceptual outcome, or as a motor event. Central to theories of speech perception and production is an attempt to describe how these aspects of speech are interrelated. The present experiment investigated how the nonstutterers' and stutterers' reproductions of acoustically presented interrogative sentences were influenced by experimental variations of intonation (sentence initial vs. sentence final) and speech rate (normal vs. time compressed). We studied the effects of these stimulus manipulations on the speech rate and fundamental frequency (F₀ ) of 10 adult German-speaking nonstutterers and seven stutterers. Experimental manipulations of intonation and speech rate significantly influenced the syllable duration and speech rate of both normal speakers and stutterers. The fundamental frequency of the subjects' responses were also significantly influenced by the intonation of the stimulus. But the stutterers' increase in F₀ for stressed syllables was generally less pronounced than that of nonstutterers. These results imply that (a) the subjects not only extract linguistic meaning from intonation but that they also store extragrammatical speech rate information, and (b) the speakers adopt these speech rate variations for their own productions. Generally, these results demonstrate that speech perception is not limited to extracting linguistically invariant information. The results show that speakers actively generate their own prosody and that this generative process is influenced by the prosodic structure of another speaker's antecedent speech. The implications of these results for theories of speech production are discussed.     

Conversations on contexts and meanings: On understanding therapeutic change from a contextual viewpoint

Recent developments within family therapy theory, often referred to as the Post-Milan Movement, have once again stressed the therapeutic encounter'squality of conversation. When therapy is looked upon as conversation, attention is not only paid to the fact that most of what happens in a session is talking. Rather, a more fundamental stance towardshuman life as basically meaning- making is taken. This is one of the essential premises of the contextualist approach to the social sciences.When applied to human problems this approach claims that symptoms evolve when (1) a person gives meaning to and performs a social act within a context inappropriate to the socially shared meaning of that act, and (2) the behavior of the person is accepted as a symptom by him/herself and the observing community. The therapeutic conversation establishes an exclusive context within which the domains of discourse of the client's life can be accounted for and renegotiated. With the acceptance of these accounts, changes evolve in the context-act relationships (i.e. meanings) construed by the client. This appears to be the basis for the self-healing aspects of psychotherapy.