Developmental changes in memory source monitoring.

Previous research suggests that children are more likely than adults to confuse memories of actions they imagined themselves performing with memories of actions they actually performed (Realization Judgments), but are not more likely to confuse memories of actions they had imagined performing with memories of actions they saw another person perform (Reality Monitoring). We approach these findings in terms of a theory about the processes by which people identify the sources of their recollections (Source Monitoring). This approach suggests that children may be more likely than adults to confuse memories from different sources whenever the sources are highly similar to one another. Experiments 1 and 2 tested this hypothesis by manipulating the perceptual and semantic similarity of two sources of information and testing 4- and 6-year-old and adult subjects' recollection of the sources of particular pieces of information. Experiment 3 tested the hypothesis that children are more likely than adults to mistakenly identify memories of things they imagined another person doing as memories of things they witnessed that person doing. The findings indicate that (a) people are more likely to confuse memories from similar than dissimilar sources, (b) source monitoring improves during the preschool and childhood years, and (c) children may be especially vulnerable to the effects of source similarity.     

Efficacy of caffeine versus expectancy in altering caffeine-related symptoms

The study investigated the independent and interactive effects of caffeine and expectancy on caffeine-related symptoms. High- and low-caffeine consumers were randomly assigned to either an expectancy or nonexpectancy instructional set and one of four caffeine doses. Subjects were administered the State-Trait Anxiety Inventory, (Spielberger & Gorsuch, 1970) and a Symptom Questionnaire (Christensen, White, Krietsch, & Steele, 1990) prior to and 45 min following consumption of one of the four caffeine doses. An analysis of covariance identified a significant main effect for the State-Trait Anxiety Inventory scores and significant main and interaction effects for four Symptom Questionnaire items. However, when the alpha levels were corrected for the increased probability of Type I error, using the Bonferroni procedure, these effects failed to achieve significance. These results suggest that previous reports of subjective caffeine effects are also suspect because of their failure to control for the increased probability of Type I error.     

The relationship between feeding rate and patch choice.

Rats in a laboratory foraging simulation searched for sequential opportunities to feed in two patches that differed in the rate at which food pellets were delivered (controlled by fixed-interval schedules) and in the size of the pellets. The profitability of feeding in each patch was calculated in terms of time (grams per minute) and in terms of effort (grams per bar press). These values were the result of the imposed fixed interval, the size of the pellets, and the rate at which the rats pressed the bar in each condition. The rats ate more food and larger meals, but not more frequent meals, at the patch offering the higher rate of food consumption, calculated as grams per minute. The relative intake at any patch was a function of the relative rate of intake during meals at that patch compared to the other patch. Rats respond to explicit manipulations of feeding time in the same manner as they respond to manipulations of feeding effort.     

The effects of schedule history and the opportunity for adjunctive responding on behavior during a fixed-interval schedule of reinforcement.

The effects of schedule history and the availability of an adjunctive response (polydipsia) on fixed-interval schedule performance were investigated. Two rats first pressed levers under a schedule of food reinforcement with an interresponse time greater than 11 s, and 2 others responded under a fixed-ratio 40 schedule. All 4 were then exposed to a fixed-interval 15-s schedule. Water was continuously available under these conditions, but after responding became stable on the fixed-interval schedule, access was experimentally manipulated. With water freely available, subjects did not display characteristic fixed-interval response rates and patterns (i.e., scalloping or break-and-run). Instead, they exhibited predictable, stable patterns of behavior as a function of their schedule histories: Subjects with the interresponse-time history exhibited low response rates, and those with the fixed-ratio history exhibited high rates. Manipulating the amount of water available resulted in marked changes in response rates for rats with the interresponse-time history but not for those with the fixed-ratio history. The results illustrate the multiple causation of behavior by its previous and current schedules of reinforcement and other concurrent factors.     

CONSPEC and CONLERN: a two-process theory of infant face recognition

Evidence from newborns leads to the conclusion that infants are born with some information about the structure of faces. This structural information, termed CONSPEC, guides the preference for facelike patterns found in newborn infants. CONSPEC is contrasted with a device termed CONLERN, which is responsible for learning about the visual characteristics of conspecifics. In the human infant, CONLERN does not influence looking behavior until 2 months of age. The distinction between these 2 independent mechanisms allows a reconciliation of the conflicting data on the development of face recognition in human infants. Finally, evidence from another species, the domestic chick, for which a similar 2-process theory has already been put forward, is discussed. The new nomenclature is applied to the chick and used as a basis for comparison with the infant.     

Three-membered domains for aristotle's syllogistic

The paper shows that for any invalid polysyllogism there is a procedure for constructing a model with a domain with exactly three members and an interpretation that assigns non-empty, non-universal subsets of the domain to terms such that the model invalidates the polysyllogism.I am grateful to T. J. Smiley and an anonymous referee for comments that improved this paper.     

Mediating mechanisms in a school-based drug prevention program: first-year effects of the Midwestern Prevention Project

Describes (a) the effects of a social-influences-based drug prevention program (the Midwestern Prevention Project) on the mediating variables it was designed to change and (b) the process by which the effects on mediating variables changed use of drugs (tobacco, alcohol, and marijuana). Students in 42 middle schools and junior high schools in Kansas City, Missouri, and Kansas City, Kansas, were measured in the fall of 1984 (N = 5,065) and again 1 year later (N = 5,008) after 24 of the schools had been through the program. Compared to students in control schools, students in program schools became less likely to express belief in the positive consequences of drug use, less likely to indicate that they would use such drugs in the future, more likely to report that their friends were less tolerant of drug use, and more likely to believe that they were better able to communicate with their friends about drug or school problems. Change in perceptions of friends' tolerance of drug use was the most substantial mediator of program effects on drug use. There was evidence that intentions to use and beliefs about the positive consequences of use may also mediate program effects on drug use.     

Outcome trees and baseball: A study of expertise and list-length effects

When people estimate the probability of an event using a list that includes all or most of the possible events, their estimate of that probability is lower than if the other possible events are not explicitly identified on the list (i.e., are collapsed into an all-other-possibilities category). This list-length (or pruning) effect has been demonstrated to occur even for people who have expertise or considerable knowledge in the event domain. We reasoned that the experts used in previous studies would be unlikely to have probabilistic representations of their problem domains (e.g., auto mechanics, auditors, hospitality managers). We used baseball experts (n= 35) and novices (n = 56) on the assumption that expertise in baseball almost certainly involves mental representations of probability for various baseball events. Subjects estimated the frequency of hits, walks, strikeouts, putouts, and “all other” outcomes for an average major league player in 100 times at bat. Other subjects estimated these event outcome frequencies in a short-list condition (e.g., strikeouts, walks, and “all other”). Strong list-length effects were observed with novices; the frequency estimate for strikeouts, for example, was nearly twice as high in the short-list condition as in the long-list condition. Experts, however, showed no list-length effect and their estimated probabilities were very near the actual (normatively correct) probabilities in all conditions. We argue that the omission effect can be overridden by strong mental representations of the family of possible events and/or a clear knowledge of the probabilities associated with the events. As well, we argue that list-length effects seem to result at least in part from an anchoring-and-adjustment strategy.     

The Health Orientation Scale: A measure of psychological tendencies associated with health

Health professionals have recently begun to examine the impact of psychological tendencies on people's physical health. The present investigation sought to facilitate this research endeavour through the development and validation of a self-report instrument designed to measure multiple health-related psychological tendencies. Reliability analyses provided evidence of internal consistency for the subscales of the Health Orientation Scale. Other results indicated that both gender and age jointly influenced people's responses to the Health Orientation Scale. A final set of results revealed that the psychological variables measured by the Health Orientation Scale were predictive of women's and men's self-reported compliance with health-promoting behaviours. The discussion focuses on the potential uses of the Health Orientation Scale in both research and applied settings.