Reinforcing variability in adolescents with autism

Five adolescents with autism, 5 adult control participants, and 4 child controls received rewards for varying their sequences of responses while playing a computer game. In preceding and following phases, rewards were provided at approximately the same rate but were independent of variability. The most important finding was that, when reinforced, variability increased significantly in all groups. Reinforced variability could provide the necessary behavioral substrate for individuals with autism to learn new responses.     

The Client Is the Most Important Common Factor: Clients' Self-Healing Capacities and Psychotherapy

I first briefly review the dodo bird verdict and suggest that we should be responding to it by looking for a new way to conceptualize how therapy works. Then I describe the dominant medical or treatment model of psychotherapy and how it puts the client in the position of a dependent variable who is operated on by supposedly potent therapeutic techniques. Next I argue that the data do not fit with this model. An alternative model is that the client is the most important common factor and that it is clients' self-healing capacities which make therapy work. I then argue that therapy has two phases—the involvement phase and the learning phase—and that the involvement phase is the most important. I next review the five learning opportunities provided by therapy. Finally, I argue that a relational model of therapy focused on consultation, collaboration, and dialogue is better than a treatment model.     

Hyperactivity in Children: A Focus on Genetic Research and Psychological Theories

Hyperactivity has attracted a large amount of research interest in recent years. Here we review developments in genetic research and in research testing psychological theories of the condition. Family, adoptee and twin studies indicate a strong role for genetic factors in the etiology of hyperactivity. Evidence is emerging also from molecular genetic studies, implicating specific genes that may be involved. At the level of cognitive functioning, a divided, focused or sustained attention deficit does not seem to be a core deficit in hyperactivity. Although children with hyperactivity often perform poorly on certain executive function tasks, there is disagreement about the interpretation of these findings. The association reported in some studies between a slow inhibitory process and hyperactivity may reflect a generally slow, variable in speed and inaccurate pattern of responding. Hypotheses about psychological mechanisms such as state regulation or delay aversion provide alternative, and particularly encouraging, interpretations of the findings. We discuss the possible integration of the two lines of research—those of genetic research and research on psychological mechanisms.     

多层线性模型在纵向研究中的运用

纵向研究中传统统计技术主要是重复测量的方差分析和多元回归分析，但是这两种技术存在一些局限性，不能合理而充分地解释纵向研究资料。近年来出现的多层线性模型能够更有效地利用纵向数据。为促进多层线性模型在纵向研究中的运用，简要论述了传统统计技术的局限，介绍了多层线性模型的原理及其在纵向研究中的作用，以一组模拟数据为例对多层线性模型中各种参数在纵向研究中的含义进行了详细讨论，对于纵向研究中运用多层线性模型时须注意的问题提出了建议。     

Representation and working memory in early arithmetic

Working memory has been implicated in the early acquisition of arithmetic skill, but the relations among different components of working memory, performance on different types of arithmetic problems, and development have not been explored. Preschool and Grade 1 children completed measures of phonological, visual-spatial, and central executive working memory, as well as nonverbal and verbal arithmetic problems, some of which included irrelevant information. For preschool children, accuracy was higher on nonverbal problems than on verbal problems, and the best and only unique predictor of performance on the standard nonverbal problems was visual-spatial working memory. This finding is consistent with the view that most preschoolers use a mental model for arithmetic that requires visual-spatial working memory. For Grade 1 children, performance was equivalent on nonverbal and verbal problems, and phonological working memory was the best predictor of performance on standard verbal problems. For both age groups, problems with added irrelevant information were substantially more difficult than standard problems, and in some cases measures of the central executive predicted performance. Assessing performance on different components of working memory in conjunction with different types of arithmetic problems provided new insights into the developing relations between working memory and how children do arithmetic.     

The Meaning vs. The Medical Model in the Empirically Supported Treatment Program: A Consideration of The Empirical Evidence

A review of the debate on the Empirically Supported Treatment Program is presented. It is argued that underlying the specifics of the debate are fundamentally incompatible paradigms: a meaning vs. a medical model. The findings from two gold standard multi-site studies are reviewed to conclude that the control condition meets requirements for an empirically supported treatment. The empirical finding of the failure of clinical training to improve treatment outcomes is explained by the focus on rational factors in training. It is recommended that training of therapists focus on enhancing experiential capacity rather than mastery of manualized treatment approaches.     

Concurrent second-order schedules: some effects of variations in response number and duration

To examine the effects on concurrent performance of independent manipulations of response-unit duration and number, 6 hens were exposed to concurrent second-order schedules of reinforcement. Each first-order operant unit required completion of a fixed-ratio schedule within the time specified by a fixed-interval schedule, with one further response completing the fixed-interval schedule. The fixed-ratio and fixed-interval requirements comprising the first-order operant units were systematically and independently varied under three pairs of concurrent variable-interval schedules to produce differences in the first-order response and duration requirements (response and duration differentials). These manipulations produced consistent changes in response, time, and operant-unit biases. A 1:4 response differential biased the time and operant-unit measures towards the smaller fixed ratio, but to a degree less than the imposed response differential. The response-based biases favored the larger fixed ratio. Duration differentials of 4:1 and 8:1 biased the response and operant-unit measures towards the shorter fixed interval, again less than the imposed duration differential, but the time biases remained close to zero. Both sorts of differentials acted to bias operant-unit completions more systematically than the other measures, but undermatching to the differentials occurred. The undermatching appears to have arisen from a pattern of fix and sample (in which visits to the less preferred alternative involved only a single completed operant unit) under combinations of unequal operant-unit requirements and reinforcer rates. The response and time bias measures appeared to arise as by-products of the changes in operant-unit completions.     

Neural correlates of a default response in a delayed go/no-go task

Working memory, the ability to temporarily retain task-relevant information across a delay, is frequently investigated using delayed matching-to-sample (DMTS) or delayed Go/No-Go tasks (DGNG). In DMTS tasks, sample cues instruct the animal which type of response has to be executed at the end of a delay. Typically, performance decreases with increasing delay duration, indicating that working memory fades across a delay. However, no such performance decrease has been found when the sample cues exist of present vs. absent stimuli, suggesting that pigeons do not rely on working memory, but seem to respond by default in those trials. We trained 3 pigeons in a DGNG task and found a similar default response pattern: The diverging slopes of the retention functions on correct Go and No-Go trials suggested that pigeons by default omitted their response following No-Go stimuli, but actively retained task-relevant information across the delay for successful responses on Go trials. We conducted single-cell recordings in the avian nidopallium caudolaterale, a structure comparable to the mammalian prefrontal cortex. On Go trials, many neurons displayed sustained elevated activity during the delay preceding the response, replicating previous findings and suggesting that task-relevant information was neurally represented and maintained across the delay. However, the same units did not show enhanced delay activity preceding correct response suppressions in No-Go trials. This activation-inactivation pattern presumably constitutes a neural correlate of the default response strategy observed in the DGNG task.     

On the existence and uniqueness of JML estimates for the partial credit model

A necessary and sufficient condition is given in this paper for the existence and uniqueness of the maximum likelihood (the so-called joint maximum likelihood) estimate of the parameters of the Partial Credit Model. This condition is stated in terms of a structural property of the pattern of the data matrix that can be easily verified on the basis of a simple iterative procedure. The result is proved by using an argument of Haberman (1977). The author wishes to thank the Editor and the anonymous reviewers for their comments that helped to substantially improve the final version of this paper. This research was supported in part by a MURST grant (ex 60%).     

Checking the Assumptions of Rasch's Model for Speed Tests

Two new tests for a model for the response times on pure speed tests by Rasch (1960) are proposed. The model is based on the assumption that the test response times are approximately gamma distributed, with known index parameters and unknown rate parameters. The rate parameters are decomposed in a subject ability parameter and a test difficulty parameter. By treating the ability as a gamma distributed random variable, maximum marginal likelihood (MML) estimators for the test difficulty parameters and the parameters of the ability distribution are easily derived. Also the model tests proposed here pertain to the framework of MML. Two tests or modification indices are proposed. The first one is focused on the assumption of local stochastic independence, the second one on the assumption of the test characteristic functions. The tests are based on Lagrange multiplier statistics, and can therefore be computed using the parameter estimates under the null model. Therefore, model violations for all items and pairs of items can be assessed as a by-product of one single estimation run. Power studies and applications to real data are included as numerical examples.