A dual-task investigation of young stutterers and nonstutterers

Twenty right-handed grade-school stutterers and nonstutterers matched for sex, handedness, and age were the subjects of this neuromotor investigation. They were required to tap a button as rapidly as possible in a single-task control condition, in three increasingly demanding dual-task conditions in which finger-tapping and speech occured concurrently, and in a dual-task condition in which the subjects finger-tapped and vocalized the sound of a siren. The conditions were randomized, and hand order was counterbalanced. The overall tapping rate of the nonstutterers was statistically faster than that of the stutterers for both the right and left hand. Relative to the single-task silent control condition, the tapping rates of both groups decreased as the dual-task speech conditions became more demanding. However, the tapping rate of the nonstutterers was significantly faster across the speech conditions. Neither the group by hand, group by condition, or group by hand by condition interaction was statistically significant. The stutterers responded like the nonstutterers, though more slowly, providing support for the current contentions that the neuromotor system of stutterers is less robust than that of nonstutterers and more affected by the demands of speech production.     

A method for studying visually guided perception and learning in newborn macaques

A maintenance technique was developed in which neonatal monkeys obtain all liquid food by placing their heads in a face mask mounted on their cage wall. Complete self-feeding required only 3-6 days for animals started at birth. Once under a self-feeding Schedule, operant responses were shaped to study visual perception, visually guided motor performance, and discrimination learning at ages much younger than those allowed by most alternative methods. Dark rearing, with the only source of visual input being through the face mask eyeholes, allowed the E to control completely the neonate’s visual experiences and its opportunities for visual-motor responding. The method has proven useful in rhesus monkey newborns for studying adaptation to prismatic displacement at 30 days of age, and to performance on CRF, FI, and FR reinforcement schedules.     

Responsibility diffusion and drive enhancement effects on risky shift1

Discussion produced expected risky and cautious shifts on choice dilemma items It was predicted from responsibility diffusion theory that, compared with low-anxious, high-defensive groups, high-anxious, low-defensive groups produce greater risky shift It was predicted from drive enhancement theory that, compared with low-anxious groups, high-anxious groups produce greater risky shift on risk-dominant items and greater cautious shift on caution-dominant items The results of two experiments failed to confirm either interpretation Surprisingly, significant shifts were obtained in a control condition     

Expressed vs inventoried interests as predictors of paramedical effectiveness

Two interest measures, a composite of six items which provide a direct assessment of an individual's preferences for Navy health care work and a Navy Vocational Interest Inventory (NVII) scale which assessed the degree of similarity between an individual's activity preferences and those of hospital corpsmen (HMs), were considered along with aptitude test scores as potential predictors of effectiveness among 2429 Navy enlisted personnel assigned to training for HM jobs. Effectiveness was defined as completion of HM training and remaining on the job for at least 2 years. The six-item composite and NVII HM scale scores were correlated .51 with each other and were correlated .27 and .28, respectively, with the effectiveness criterion. When these measures were added to the aptitude measure by using multiple regression procedures, the validity for predicting effectiveness was increased significantly from .36 to .42 with a cross-validity of .42 for the three-variable equation. These findings provide support for the contention that interest measures can be useful predictors of occupational success as well as occupational entry. Furthermore, since most of the interest-related attrition that was found in this study occurred during HM training, these findings suggest that job withdrawal attributable to mismatches in vocational interests may tend to occur very soon after the individual enters the occupational field.     

The foundations of Quine's philosophy

Tensions in Two Dogmas of Empiricism are not resolved in Quine's later writings. The role of simplicity remains mysterious. Naturalized epistemology is wrongly presented as the only alternative to phenomenalism, and no attempt is made to answer the objection that judgements of the rationality of human activities have no place within a naturalistic philosophy. The attempt to develop an empiricism without experience leads to an implausible behaviorism and to an unsuccessful naturalistic account of observation sentences.A part of an earlier version of this paper was read at the Annual Conference of the Australasian Association of Philosophy, (August, 1973), and a part at the Annual Conference of the New Zealand Division, (May, 1975). I have been helped by the encouragements and criticisms offered by M. C. Bradley, G. C. Nerlich, J. J. C. Smart, and the Editor.