Response to Boyd's Commentary

Philosophical Studies -     

Observations on the initiation of eating of new food by weanling kittens

The reaction to a new food and the initiation of its consumption were studied in daily sessions in 19 weanling kittens from four litters at 30–39 days of age. The new food consisted of canned tuna for two litters and cereal (cooked cream of wheat with 3% addition of vegetable oil and broth flavor) for the other two litters. Each litter was divided into two groups. One group was offered the new food in the presence of the mother which had been consuming it (eating cereal had to be induced in the mothers by the hypothalamic stimulation reward method). Another group of kittens received the same food in the absence of the mother. It was found that the kittens which had been offered the new food in the presence of the mother showed only a short-lasting orienting reaction and started to eat the new food on the first or second day (with a mean delay of 0.2 days). On the other hand, the kittens which had been offered the new food in the absence of the mother showed a strong orienting reaction and started to eat the new food only after several daily sessions (with a mean delay of 4.8 days). No significant difference was found between the number of days of delay in eating by kittens offered tuna and by kittens offered cereal in the absence of the mother. The initiation of consumption of the new food by these kittens was preceded by a period of playing with the plate on which the food had been placed. Additional observations showed that the fourto five-month old kittens that had eaten cereal during early training preferred that food over meat pellets; the other kittens of the same age that had eaten tuna, but no cereal, during early training refused to eat cereal when it was offered to them when they were hungry.     

Hearing by eye

Recent work on integration of auditory and visual information during speech perception has indicated that adults are surprisingly good at, and rely extensively on, lip reading. The conceptual status of lip read information is of interest: such information is at the same time both visual and phonological. Three experiments investigated the nature of short term coding of lip read information in hearing subjects. The first experiment used asynchronous visual and auditory information and showed that a subject's ability to repeat words, when heard speech lagged lip movements, was unaffected by the lag duration, both quantitatively and qualitatively. This suggests that lip read information is immediately recoded into a durable code. An experiment on serial recall of lip read items showed a serial position curve containing a recency effect (characteristic of auditory but not visual input). It was then shown that an auditory suffix diminishes the recency effect obtained with lip read stimuli. These results are consistent with the hypothesis that seen speech, that is not heard, is encoded into a durable code which has some shared properties with heard speech. The results of the serial recall experiments are inconsistent with interpretations of the recency and suffix effects in terms of precategorical acoustic storage, for they demonstrate that recency and suffix effects can be supra-modal.     

Book reviews

Horowitz, M. J. (Ed.) (1988). Psychodynamics and cognition. Chicago: University of Chicago press. Pp. 389. ISBN 0226-35368-0. £ 21.95

Ellis A. W. & Young, A. W. (1988). Human cognitive neuropsychology. Hove: Lawrencve erlbaum Associates Ltd. Pp. 358. ISBN 0-86377-033-9, £ 21.95 9 (hardback), 0-86377-034-7, £ 11.95 (paperback).

Humphreys, G. W., & Bruce, V.(1989). Visual cognition: Computational, experimental and neuropsychological perspectives. Hove & London: Lawrence Erlbaum Associates Ltd. Pp. 330. ISBN 0-86277-124-6, £ 19.95 (hardback), 0-86377-125-4, £ 9.95 (paperback)     

Symbol-string sensitivity and adult performance in lexical decision

In this study of adult readers, we used a symbol-string task to assess participants' sensitivity to the position of briefly presented, non-alphabetic but letter-like symbols. We found that sensitivity in this task explained a significant proportion of sample variance in visual lexical decision. Based on a number of controls, we show that this relationship cannot be explained by other factors including: chronological age, intelligence, speed of processing and/or concentration, short term memory consolidation, or fixation stability. This approach represents a new way to elucidate how, and to what extent, individual variation in pre-orthographic visual and cognitive processes impinge on reading skills, and the results suggest that limitations set by visuo-spatial processes constrain visual word recognition.     

Counterfactual and semifactual conditionals prime alternative possibilities

The authors examined in 3 experiments the comprehension of counterfactuals, such as "If it had rained, the plants would have bloomed," and semifactuals, such as "Even if it had rained, the plants would have bloomed," compared with indicative conditionals, "If it rained, the plants bloomed." The first experiment showed that people read the negative conjunction, "not p and not q" faster when it was primed by a counterfactual than when it was primed by an indicative conditional. They read the affirmative conjunction, "p and q" equally quickly when it was primed by either conditional. The 2nd experiment showed that people read the negated-antecedent conjunction, "not p and q" faster when it was primed by a semifactual conditional. The 3rd experiment corroborated these results in a direct comparison of counterfactuals and semifactuals. The authors discuss the implications of the results for the mental representations of different conditionals.     

Cognitive ability, expertise, and age differences in following air-traffic control instructions

Differences in cognitive ability and domain-specific expertise may help explain age differences in pilot performance. Pilots heard air-traffic controller messages and then executed them while "flying" in a simulator. Messages varied in length and speech rate. Age was associated with lower accuracy, but the expected Age x Message Difficulty interactions were not obtained. Expertise, as indexed by pilot ratings, was associated with higher accuracy; yet expertise did not reduce age differences in accuracy. The effect of age on communication task accuracy was largely explainable as an age-associated decrease in working memory span, which in turn was explainable as decreases in both speed and interference control. Results are discussed within frameworks of deliberate practice and cognitive mediation of age differences.     

Modification of coronary-prone behaviors in coronary patients of low socio-economic status

The purpose of this study is to determine the effectiveness of a group cognitive-behavioral treatment to modify coronary-prone behaviors in patients from a fairly low social and educational level. Participants were 98 male coronary patients randomly allocated to one experimental and two control groups. All groups received standard medical treatment. The experimental group received an additional psychological treatment and one of the two control groups received a health education treatment. Results showed that only the psychological treatment group significantly reduced Pressured Drive and Speed-Impatience after treatment, and at 1- and 2-year follow-ups. Depression was also significantly reduced only in this group at 2-year follow-up. The results are considered a reliable first step in the process of validating this program designed to improve coronary heart disease patients' quality of life.