On the Bradley hypothesis concerning agrammatism: the nonword-interference effect

In 1980, D. C. Bradley, M. F. Garrett, and E. B. Zurif (in D. Caplan (Ed.), Biological studies of mental processes, Cambridge, MA: MIT Press) have proposed a lexical hypothesis on agrammatism. The theoretical background of this hypothesis is described. Then two experiments are reported with normal speakers on the so-called nonword-interference effect that has been one of the two major sources of experimental evidence for this hypothesis. The first experiment replicates the original finding that the interference effect is found when the nonword starts with a content word but not when it starts with a function word. In the second experiment, it is shown that this contrast is due to an artifact of the composition of the word list. When this list contains both content and function words, rather than only content words--as in Bradley's experiments and our Experiment I--both content and function nonwords show an equally sized interference effect. The consequences for the lexical hypothesis are discussed.     

Performance differences following exposure to predictable and unpredictable noncontingent outcomes in high and low achievers

Two experiments are described in which subjects rated as high or low in achievement motivation were exposed to uncontrollable outcomes on a cognitive task. Effects on subsequent performance on a different cognitive task were shown to depend on level of achievement motivation, on whether the uncontrollable outcomes were predictable or unpredictable, and on whether the uncontrollable outcomes were positive or negative. These findings have important theoretical implications which are discussed.     

An individualized regression and clustering assessment of the social values of adults and children

Research investigating social values in interdependency situations has generally demonstrated age differences across the 5- to 10-year-old age range. However, the precise nature of these differences is unclear. Further, the differences in the social values of adults and children has not been addressed. The present study examined the social values of undergraduates and children using a measurement technique designed to allow an accurate inference of social values. Ninety-one 6- to 10-year-old children and 100 undergraduates rated the desirability of a set of outcomes which systematically varied with regard to the benefits to themselves and another person. Theoretically specified characteristics of the outcomes were then used to generate a regression equation predicting the desirability ratings separately for each individual. These regression equations were then clustered into groups of individuals who used decision rules characteristic of the major social values. The results indicate that the 8- to 10-year-old children, compared to the 6- to 7-year olds, more often expressed a social value involving equality and tended to less often express a social value involving superiority. Comparison of the social values expressed by the children and adults indicated that the adults more often expressed group-enhancement and individualism social values and less often expressed a social value involving superiority.     

When celebrities talk,children listen: An experimental analysis of children's responses to TV ads with celebrity endorsement

Two studies tested the effects of TV ads with celebrity endorsement on the product preference and understanding of 8- to 14-year-old boys. Study 1 compared two ads for a model racer. One had celebrity endorsement (by a famous race driver) and footage of real automobile racing featuring the celebrity (live action); the second had neither feature. Study 2 employed one ad for a different brand of model racer edited to generate a 2 (endorser presence) by 2 (inclusion of live racetrack action) factorial design. A total of 415 boys were exposed to one of the experimental ads or a control ad, embedded in a new animated children's adventure program. Preference for the advertised brand of model racer (pre- and postviewing) and a number of cognitive variables were assessed. Exposure to endorsement led to increased preference for the toy and belief that the celebrity was expert about the toy. Live action led to exaggerated estimates of the physical properties of the toy and the belief that the ad was not staged. The 8- to 10-year-olds associated the glamour of the endorser with the toy and were more reliant on his advice than were 11- to 14-year-olds. However, the two age groups were not differentially affected by the ads. Contrary to the speculation of many researchers, understanding about advertising intent and techniques and cynicism about ads had almost no influence on product preference after viewing.     

Sensitivity in spectral structures

Invariance of matching is shown to be necessary and sufficient for the existence of sensitivity functions that are unique up to multiplication by arbitrary positive real numbers. Examples from auditory and visual psychophysics are discussed.     

A maximum likelihood hierarchical disaggregate model for predicting choices of individuals

The absence of operational disaggregate lexicographic decision models and Tversky's observation that choice behavior is often inconsistent, hierarchical, and context dependent motivate the development of a maximum likelihood hierarchical (MLH) choice model. This new disaggregate choice model requires few assumptions and accommodates the three aspects of choice behavior noted by A. Tversky (1972, Journal of Mathematical Psychology, 9, 341–367). The model has its foundation in a prototype model developed by the authors. Unlike the deterministic prototype, however, MLH is a probabilistic model which generates maximum likelihood estimators of the aggregate “cutoff values.” The model is formulated as a concave programming problem whose solutions are therefore globally optimal. Finally, the model is applied to data from three separate studies where it is demonstrated to have superior performance over the prototype model in its predictive performance.     

Five-month-old infant recall and utilization of temporal organization

The ability of 5-month-old infants to recall temporal information and utilize temporal organization was investigated in two experiments. Infants were trained to fixate a hierarchically structured or an unstructured sequence of stimuli which appeared in four spatial positions. In the first study, the number of infants who demonstrated correct recall through the third serial position of a sequence was significantly better then would occur by chance. In the second study, infants given structured sequences showed a significant increase in the number of correct fixations across trials, and they recalled across serial positions better in structured sequences. Also, accuracy of recall in both studies for the middle serial positions was related to hierarchical organization following 8-unit structured sequence training but was at chance level following unstructured sequence training. Results of both studies were interpreted within a temporal organizational framework: Infants appear to utilize organization within sequences of information.     

Food anticipation and lever-directed activities in rats

Three experiments are described which elaborate some of the conditions under which rats will contact and manipulate a periodically presented retractable lever. Experiment 1 demonstrated that (i) initial manipulative oral and manual contact with the lever was facilitated if the rat had previous experience of food delivery in the experimental chamber; (ii) persistence in contacting the lever on successive presentations was a function of whether food continued to be presented in the experimental environment; and (iii) food satiation significantly reduced the tendency of the rat to contact the lever even though an expectancy of food had previously been established under conditions of food deprivation. Experiment 2 suggested that the tendency to approach and contact the lever was in part a function of the local moment-to-moment conditional probability of food delivery. Experiment 3 found that the probability of contacting the lever was higher during presentation of an auditory CS signaling a high rate of food delivery than during stimuli signaling no food at all. These results are interpreted as suggesting that the food-signaling aspects of an appetitive CS and that CS's ability to generate signal-directed behaviors are experimentall separable properties.     

Mechanisms of blocking by contextual stimuli

The influence of contextual stimuli on the conditioning and performance of responding to a discrete stimulus was examined in the US preexposure paradigm using both context shift manipulations and a measure of context conditioning. Four groups of rats received both repeated exposure to an electric shock US in one context (Context 1), and repeated nonshocked exposure to a second context (Context 2). Two additional groups of rats received exposure to these contexts, but never received shock presentations. Rats exposed to shock learned to escape from the stimuli of Context 1, but did not escape from the stimuli provided by Context 2. Rats not exposed to shock failed to escape from either context. All rats then received a single CER conditioning session in which four pairings of a 3-min noise CS and shock US were presented. Half the rats received those CS-US pairings in the excitatory Context 1, while the remaining rats received those pairings in the neutral Context 2. Finally, half the rats in each of the CER conditioning treatments received extinction test trials of the noise CS in Context 1, while the remaining rats received those test trials in Context 2. Thus, this design factorially manipulated the presence of excitatory or neutral contextual stimuli during both conditioning and testing of a discrete CS. In comparison with the two groups of rats never preexposed to shock alone, attenuation in acquisition of conditioned suppression observed during test trials occurred only when CER conditioning had been administered in the excitatory Context 1, and this effect was manifested when testing occurred in either the excitatory Context 1 or the neutral Context 2. These results support the model of R. A. Rescorla and A. R. Wagner (1972) (in A. H. Black & W. F. Prokasy (Eds.) Classical Conditioning II, pp. 64–99, New York: Appleton-Century-Crofts) which asserts that contextual stimuli and sicrete CSs compete for limited associative strength supportable by a given US.