Sensitivity to shifts of a point stimulus: An instance of tactile hyperacuity

The sensitivity of the tactile sense to shifts in the position of a point stimulus was determined at four body loci: the index finger, forehead, belly, and back. Water-jet stimulation was used, a method which allows frictionless travel of a point stimulus over the skin. Three subjects were tested by means of the method of forced choice, with the task being to say whether the stimulus moved to the right or to the left. The shift threshold was defined as that shift excursion which gave rise to 75% correct responding. The basic finding was that shift thresholds were on the order of 10 to 30 times smaller than the corresponding two-point limens obtained by Weinstein (1968) for the same body loci. These unexpectedly small shift thresholds indicate an exquisite sensitivity of the cutaneous sense to rapid changes in position of a point stimulus. A physiological model is presented which accounts for the difference between localization and spatial resolution. nt]mis|This research was supported by Department of Health~ Education, and Welfare Grant 14-P-SS282/9 from the Social and Rehabilitation Services, NIH Research Grant R01-EY-00686 from the National Eye Institute, and the Smith-Kettlewell Eye Research Foundation.     

Some aspects of self aversive stimulation in the hooded rat

Three hooded rats were trained to bar press for variable-ratio liquid reinforcement after which an electric shock was delivered following the response. Initially, the shock was presented on a FR 100 basis but the frequency was gradually increased until all responses were punished. Finally, a partial extinction procedure was conducted to determine if the shock resulted in increased bar pressing. No durable suppression of responding occurred, although one subject's rate was reduced during continuous shock. The overall trend for the three animals was one of increased responding. Changes in the pattern of responding were also observed suggesting that the suppressive effects of the punishment were largely restricted to the first response following reinforcement. Increased responding as a function of shock reintroduction during extinction was also observed.     

Significant Content of Group Counseling Sessions with Culturally Deprived Ninth Grade Students

Some examples are presented of the problems and concerns that were verbalized and discussed during group counseling sessions with 4 groups (36 students) of culturally deprived white ninth grade boys and girls. The examples cited indicate that among these culturally deprived students there is a general lack of identification with school, a pattern of employing inappropriate means to gain acceptance and recognition, a philosophy of life geared toward immediate material gratification, and parental models that do not result in positive parental identification. There seems to be little hope for these students in their present situation unless they receive some help and support from interested others outside their group. It is suggested that group counseling, for considerably more than the 15 sessions given these students, may afford a means by which the school and the counselor can help the culturally deprived find an effective way to deal with the dilemma in which they find themselves.     

Case Groups: An In-Service Education Technique

An elementary public school utilized Case Groups as part of a comprehensive in-service education program for its staff. The Case Group was designed as a paced learning experience incorporating elements from discussion, case study, and sensitivity training groups in the attempt to facilitate both cognitive and experiential aspects of the teachers' continuing professional growth. The kinds of growth experienced by the participants are described and subjectively evaluated to the conclusion that the Case Group, or modifications thereof, has high potential for the in-service education of teachers.     

The Genesis of Possible Worlds Semantics

This article traces the development of possible worlds semantics through the work of: Wittgenstein, 1913–1921; Feys, 1924; McKinsey, 1945; Carnap, 1945–1947; McKinsey, Tarski and Jónsson, 1947–1952; von Wright, 1951; Becker, 1952; Prior, 1953–1954; Montague, 1955; Meredith and Prior, 1956; Geach, 1960; Smiley, 1955–1957; Kanger, 1957; Hintikka, 1957; Guillaume, 1958; Binkley, 1958; Bayart, 1958–1959; Drake, 1959–1961; Kripke, 1958–1965.