Response additivity: effects of superimposed free reinforcement on a variable-interval baseline

Three experiments examined the effects of superimposing free reinforcement (Free VI 30-sec) on behavior maintained by a response dependent mult VI 2-min VI 2-min schedule of reinforcement. Experiment I used pigeons as subjects, key pecking as the response, and colors of response key as the stimuli associated with the multiple-schedule components. When free reinforcement was added during only one component (Differential condition) a large and highly significant increase in response rate developed in this component. Adding free reinforcement during both components (Nondifferential condition) produced smaller and far less-consistent effects. An entirely different pattern of results was obtained in two subsequent experiments, where similar procedures and reinforcement conditions were used with rats as subjects and bar pressing as the response. In both Experiments II and III, response rates decreased to the stimulus associated with added free reinforcement in the Differential condition. These findings are interpreted as the result of interactions between behavior maintained by response-reinforcer contingencies and behavior maintained by stimulus-reinforcer contingencies. As such, they support the main assumption of an autoshaping theory of behavioral contrast, that additivity of responding generated by the two kinds of contingency can occur only in situations favorable to autoshaping.     

Grouping of stimuli and apparent exceptions to the psychological refractory period

When a subject is called upon to respond independently to two stimuli, the second of the two responses is often delayed if the stimuli follow closely on one another, and this has led to the suggestion that in making decisions the human operator accepts and organizes the available input information intermittently in the manner of a discontinuous servo. According to this view two nearly simultaneous stimuli can only be dealt with equally fast if they are grouped into a single decision to respond to both stimuli; otherwise one will have to wait for the attention of the central mechanism until the other has been dealt with. In the present experiment it is shown that delays in the second response are not necessary or invariable, and that the pattern and timing of the second responses when they are performed without delay differ in important respects from those to be expected of grouped responses. It is concluded that the central mechanisms concerned in the response do not possess the limitations that the single channel theory would suggest.     

Parents' Experiences with Genetic Counseling After the Birth of a Baby with a Genetic Disorder: An Exploratory Study

Little is known about factors determining which families utilize genetic counseling services. We conducted semistructured interviews with parents of four children born with cystic fibrosis (CF) and ten with Down's syndrome (DS) to ascertain reasons for using, or not using, genetic counseling services in the state of Victoria, Australia. We also explored the usefulness of genetic counseling for the families who had experienced it, and the perceived role of genetic counseling. All mothers of children with CF see a genetic counselor as part of a structured education program following diagnosis through newborn screening. Information overload was identified by them as an important problem. There is no specific program for families of children with DS. Six of them had received genetic counseling and four had not, either because it was not specifically offered to them or because they did not pursue it in the context of misconceptions about its purpose. The timing of the offer of genetic counseling is important and needs to take into account parents' coping strategies after diagnosis. Several parents commented on the favorable aspects of counseling, including getting information they needed to deal with the diagnosis and relief of guilt. Better awareness of genetic counseling by referring physicians, and providing counseling at more than one visit, may contribute to a more effective service.     

Using Corticomuscular and Intermuscular Coherence to Assess Cortical Contribution to Ankle Plantar Flexor Activity During Gait

The present study used coherence and directionality analyses to explore whether the motor cortex contributes to plantar flexor muscle activity during the stance phase and push-off phase during gait. Subjects walked on a treadmill, while EEG over the leg motorcortex area and EMG from the medial gastrocnemius and soleus muscles was recorded. Corticomuscular and intermuscular coherence were calculated from pair-wise recordings. Significant EEG–EMG and EMG–EMG coherence in the beta and gamma frequency bands was found throughout the stance phase with the largest coherence towards push-off. Analysis of directionality revealed that EEG activity preceded EMG activity throughout the stance phase until the time of push-off. These findings suggest that the motor cortex contributes to ankle plantar flexor muscle activity and forward propulsion during gait.     

Book reviews

DIAMOND, S. J. The Social Behaviour of Animals. London: Baqtsford. 1970. Pp. 256. £2.50.

JARRARD, L. E. (Ed.). Cognitive Processes in Non-human Primates. New York: Academic Press. 1971. Pp. 188.

BROZEK, J. and SLOBIN, D. I. (Eds). Psychology in the USSER: An Historical Perspective. New York: International Arts and Sciences Press. 1972. Pp. x + 30.1. $ 15.00.

A. R. JENSEN. Genetics and Education. London: Methuen. 1972. Pp. Vii + 379. £ 3.50.

OATLEY, K. Brain Mechanisms and Mind. London: Thames and Husdson. 1972. Pp. 216. £2.25.

BOAKES, R. A. and HALLIDAY, M. S., (Eds). Inhibition and Learning. London: Academic Press 1972. Pp. 568. £7.25.

TOBACH, E., ARONSON, L. R. and SHAW, E. (Eds). The Biopsychology of Development. New York: Academic Press. 1971. Pp.xix + 593. dollar 22.50.

MOLTZ, H. (Ed.). The Ontogeny of Vertebrate Behavior. New York and London: Academic Press. 1971. Pp. 500. $ 22.50.

SOKOLOV, A. N. Inner Speech and Thought. London: Plenum Publishment Co. 1972. Pp. 283. £ 10.50

SHOUKSMITH, G. Intelligence, Creativity and Cognivity and Cognitive Style. LOndon: Batsford. 1970.Pp. 240. £ 2.30,

BOLTON, N. The psychology of Thinking. Lond Methuuen. 1972. Pp. 291. £3.20.

JOHNSON, D. M. Systematic Introduction to The Psychology of Thinking. New York: Harper and Row, 1972. Pp. 498. £ 5.10.

LLOYD, B. Preception and Cognition. Harmondsworth: Penguin Books. 1972. Pp. 190. £ 0.80.     

Visual working memory in young children

Five experiments investigated immediate memory for drawings of familiar objects in children of different ages. The aims were to demonstrate younger children’s greater dependence on visual working memory and to explore the nature of this memory system. Experiment 1 showed that visual similarity of drawings impaired recall in young (5-year-old) children but not in older (10-year-old) children. Experiment 2 showed that younger and older children were affected in contrasting ways when the temporal order of recall was manipulated. Experiment 3 explored a recency effect found in backward recall and investigated its sensitivity to the presentation modality of materials used to produce retroactive interference (RI). For younger children, recency was reduced by visual but not by auditory-verbal RI; for older children, recency was more sensitive to auditoryverbal RI. Experiment 4 confirmed the effect of visual RI on visual recency in young children and showed that the same RI had little effect on their recall of spoken words. These results confirm younger children’s dependence on visual working memory. A final experiment showed that the effects of visual similarity and visual RI are additive, suggesting that they reflect different modes of accessing stored visuospatial information. Implications of these findings for developmental issues and for the nature of visual working memory are discussed.     

Cheshire Cat supervenience

Conclusion Supervenience therefore is a concept with little to offer. It lacks conceptual clarity and is unable to explain the dependency relation without relying on it too heavily. Its mechanism of operation is unclear unless a projectivist analysis is used, but serious problems remain with such an account, and, even if it does apply to aesthetic or moral properties, and even secondary properties, we cannot see how it might apply to the chemical and physical world and to the mind/brain problem. Whatever characteristics make it plausible in one realm debar it from the other, and even if it is restricted to the ethical realm we cannot see how supervenience applies to our prudential values, the basic attitudes that orient our moral and aesthetic outlook.This is the second aspect to the Cheshire Catness of supervenience; the harder you look at it the more insubstantial it becomes. It fades away into the background, leaving just its smile. But, like any smile, there is more gap than substance, and supervenience does nothing to fill that gap. Still the smile lingers, the haunting question of the connection between natural and moral-aesthetic properties. This is an important question and needs to be addressed, but supervenience does not address it. It merely labels it, and, by labelling it confers a spurious air of lucidity without shedding any but the most fractured light.