Is the cerebellum a smith predictor?

The motor system may use internal predictive models of the motor apparatus to achieve better control than would be possible by negative feedback. Several theories have proposed that the cerebellum may form these predictive representations. In this article, we review these theories and try to unify them by reference to an engineering control model known as a Smith Predictor. We suggest that the cerebellum forms two types of internal model. One model is a forward predictive model of the motor apparatus (e.g., limb and muscle), providing a rapid prediction of the sensory consequences of each movement. The second model is of the time delays in the control loop (due to receptor and effector delays, axonal conductances, and cognitive processing delays). This model delays a copy of the rapid prediction so that it can be compared in temporal register with actual sensory feedback from the movement. The result of this comparison is used both to correct for errors in performance and as a training signal to learn the first model. We discuss evidence that the cerebellum could form both of these models and suggest that the cerebellum may hold at least two separate Smith Predictors. One, in the lateral cerebellum, would predict the movement outcome in visual, egocentric, or peripersonal coordinates. Another, in the intermediate cerebellum, would predict the consequences in motor coordinates. Generalization of the Smith Predictor theory is discussed in light of cerebellar involvement in nonmotor control systems, including autonomic functions and cognition.     

Classical Psychophysics and the Assessment of Agreement and Accuracy In Judgments of Personality

ABSTRACT The just noticeable difference (jnd) unit of classical psycho-physics is introduced as a new way to describe accuracy and agreement in observer evaluations of personality. A formula for estimating jnd's from typically available summary statistics is derived from Thurstone's law of comparative judgment. A study examining four traits judged in 10 samples of subjects where the design permitted the calculation of jnd's by the method of paired comparisons indicated that the formula predicted the empirically derived jnd's associated with the mean judge ratings with considerable precision. Jnd's of criterion measures were also predicted, and while fit was somewhat less impressive in this case, there was still appreciable convergence between predicted and empirical values. The implications of jnd measures of agreement and accuracy are discussed. These implications include (a) possibilities for increased understanding of bias in observer judgments, (b) a new recognition that equal correlations to external criteria do not necessarily imply equal accuracy, and (c) alternative ways of describing the magnitude of effect in psychological research.     

The rationing of health care: A doctor's dilemma

Physicians are currently presented with very difficult ethical issues regarding who receives what level of medical care and for how long. A meaningful response to these perplexing issues necessitates a collaboration of doctors with others steeped in religious and ethical traditions. This paper addresses the complicated issue of the rationing of health care, and this issue is then addressed by responses from representatives of the religious community. This symposium took place at the New York Hospital—Cornell Medical Center in March 1991.The Rev. Curtis W. Hart, M.Div. is Director of Pastoral Care and Education at the New York Hospital—Cornell Medical Center.The Rev. Paul Conner, O.P., is Associate Professor and Director of the Master's Program in Public Health Care Ethics at New York Medical College. Larry Rasmussen, Th.D., is Reinhold Niebuhr Professor of Social Ethics at Union Theological Seminary in New York. Dr. Harlan J. Wechsler is Rabbi of Congregation Or Zarua and Visiting Professor of Philosophy at Jewish Theological Seminary in New York.     

Transitional phenomena as evidenced in prayer

In this paper, we demonstrate that the study of prayer facilitates understanding of the deeply personal object related nature of religious experience. Within prayer, individuals enter the transitional sphere and meet their God representation. Both conscious and unconscious aspects of prayer can be made available through the use of a projective test developed by the authors, known as STARR: Spiritual Themes and Religious Responses test. The data obtained suggest the usefulness of Winnicottian concepts of transitional phenomena, playing, communicating, and capacity to be alone as a contemporary psychoanalytic framework for interpreting religious experience.     

What is a difficult mental health case? An empirical study of relationships among domain variables

A difficult case in psychotherapy can be defined in many ways. This study proposes a model for that definition, in which three domains (patient characteristics, case characteristics, and therapist characteristics) are considered to impact on that definition. A total of 264 professionals received a questionnaire to assess the relative importance of a series of variables within and across these domains. Wilcoxon Matched-Pairs Signed-Ranks tests indicated that patient characteristics were considered more important than therapist or case characteristics in defining a difficult case. Case characteristics were considered more important than therapist characteristics. Pearson correlations, however, suggested that the three domains in the model are related. Correlations (for years of experience) and Kruskal-Wallis one-way ANOVA for ranks (for professions) also indicated that participants were able to identify variables within domains as important in that definition regardless of years of experience or professions. Across domains, the most important variables included the motivation of the client (a patient characteristic), dropout/attrition and multiple diagnoses (case characteristics), and the degree of therapist-client racial similarity (a therapist characteristic).     

The use of subtle items in detecting deception

When subjects attempt to fake psychopathology on the MMPI, scores on subtle subscales tend to be lower than those of nonfaking subjects. Our study hypothesized that this paradox comes about because the subtle subscales have no predictive validity, but their face validity for psychopathology is the opposite of the keyed direction for psychopathology. Subjects who attempt to fake psychopathology do so on the basis of item content and thus achieve lower rather than higher scores. Three groups of 80 undergraduates took the MMPI under regular, faking-good, or faking-bad instructions. As expected, faking-bad subjects scored significantly lower than regular subjects on the 100 most subtle items, and this was due to their responses to those. 73 of the items whose face validity was misleading. The results are consistent with other work showing valid uses of subtle items in detecting deception.     

Profile of Rural College Reach-Out Students

This study focuses on the personality profile and career aspirations of rural, underachieving seventh-grade students from low socioeconomic families who were selected to participate in a college reach-out program. Implications for career counseling and educational planning are discussed.