The impact of self-efficacy and implementation intentions-based interventions on fruit and vegetable intake among adults

This study tested the effect of interventions designed for people who do not eat yet the recommended daily fruit and vegetable intake (FVI) but have a positive intention to do so. Adults (N?=?163) aged 20–65 were randomised into four groups: implementation intentions (II group), self-efficacy (SE group), combination of II?+?SE group) and a control group receiving written information on nutrition. Study variables were measured at baseline, post-intervention and at 3-month follow-up. At follow-up, compared to the control group, FVI increased significantly in the II and II?+?SE groups (1.5 and 1.9 servings per day, respectively). Most psychosocial variables significantly increased compared to the control group, with the exception of SE for vegetable intake (VI). Moreover, at 3-month follow-up, change in FVI was mediated by changes in fruit intake (FI) intention and VI action planning. In conclusion, II interventions were efficient to increase FVI, with or without consideration for the development of SE. Thus, future studies should favour the adoption of this approach to bridge the intention–behaviour gap for FVI.     

The tune in-and-out model: A random walk and its application to a presidential election survey

The stochastic model for the evolution of preferences proposed by Falmagne, Regenwetter, and Grofman [1997. Journal of Mathematical Psychology, 41, 129-143] and tested by Regenwetter, Falmagne, and Grofman [1999. Psychological Review, 106, 362-384], as well as the alternative Thurstonian model of Böckenholt [Falmagne, J.-C., Regenwetter, M., & Grofman, B. (1997). A stochastic model for the evolution of preferences. In A. A. J. Marley (Ed.), Choice, decision and measurement: Essays in honor of R. Duncan Luce (pp. 113-131). Mahwah, NJ: Lawrence Erlbaum.], gave a good statistical account of attitudinal panel data from the 1992 US presidential election. We show, however, that both models have the defect of underestimating the number of respondents who did not change their order of preference for the candidates across different polls. We present a generalization of Falmagne et al.'s model based on the idea that some individuals may become momentarily impervious to all matters related to the campaign and ‘tune out.’ This behavior could be triggered by some personal reason or by some external event related to the campaign. Like the original model, the resulting model is a random walk, but on an augmented set of states. A respondent in a ‘live’ state behaves as in the previous model, except when receiving a ‘tune-out’ token, which effectively freezes the respondent's preference state until it is reversed by a ‘tune-in’ token. We describe and successfully test the new model on the same 1992 National Election Study panel data as those used by Böckenholt (2002) and Regenwetter et al. (1999).     

Mathematical psychology—A perspective

The highpoints of mathematical psychology between the first issue of the Journal of Mathematical Psychology in 1964 and the present are outlined, with an attempt to highlight its achievements, to understand its failures and to anticipate—and possibly influence—its fate.     

Stereotype threat undermines intellectual performance by triggering a disruptive mental load

Research on stereotype threat has repeatedly demonstrated that the intellectual performance of social groups is particularly sensitive to the situational context in which tests are usually administered. In the present experiment, an adaptation of the Raven Advanced Progressive Matrices Test was introduced as a measure of cognitive ability. Results showed that individuals targeted by a reputation of intellectual inferiority scored lower on the test than did other people. However, when the identical test was not presented as a measure of cognitive ability, the achievement gap between the target and the control group disappeared. Using heart rate variability indices to assess mental workload, our findings showed that the situational salience of a reputation of lower ability undermined intellectual performance by triggering a disruptive mental load. Our results indicate that group differences in cognitive ability scores can reflect different situational burdens and not necessarily actual differences in cognitive ability.     

On realizable biorders and the biorder dimension of a relation

The paper discusses the mathematical foundations of a technique of multidimensional scaling, generalizing Guttman scaling, in which the structure of the embedding space relies only on ordinal concepts. An empirical relation is represented as an intersection of a minimal number (called bidimension) of Guttman relations. Fairly complete results are given for the cases of bidimensions 1 and 2. In the general case, the main results are based on the equivalence between the bidimension and the dimension of a certain partial order. A characterization of the bidimension as the chromatic number of some hypergraph is also provided.     

A test of the quasi-circumplex structure of human values

Schwartz’s value system (SVS) has been widely used in different disciplines (e.g., psychology, management, and marketing). Although the value structure seems to be validated when data are analyzed through multidimensional scaling, we show that the quasi-circumplex structure of human values is not supported when confirmatory analysis approaches (e.g., CIRCUM and constrained confirmatory factor analysis) are used. Based on two samples of French and Swiss respondents, confirmatory tests of SVS provide little support for its quasi-circumplex structure, mainly due to problems of construct and discriminant validity resulting from multicollinearity between value types.     

Ageing-related stereotypes in memory: When the beliefs come true

Age-related stereotype concerns culturally shared beliefs about the inevitable decline of memory with age. In this study, stereotype priming and stereotype threat manipulations were used to explore the impact of age-related stereotype on metamemory beliefs and episodic memory performance. Ninety-two older participants who reported the same perceived memory functioning were divided into two groups: a threatened group and a non-threatened group (control). First, the threatened group was primed with an ageing stereotype questionnaire. Then, both groups were administered memory complaints and memory self-efficacy questionnaires to measure metamemory beliefs. Finally, both groups were administered the Logical Memory task to measure episodic memory, for the threatened group the instructions were manipulated to enhance the stereotype threat. Results indicated that the threatened individuals reported more memory complaints and less memory efficacy, and had lower scores than the control group on the logical memory task. A multiple mediation analysis revealed that the stereotype threat effect on the episodic memory performance was mediated by both memory complaints and memory self-efficacy. This study revealed that stereotype threat impacts belief in one's own memory functioning, which in turn impairs episodic memory performance.     

Recasting (the near-miss to) Weber's law

The authors argue mathematically that a common, power-function model of the just-noticeable difference in stimulus intensities is logically inconsistent with an exponent other than 1 in those frequent situations in which a particular averaging over experimental conditions has taken place. The authors show that an alternative power-law model, one which does not share this logical inconsistency, provides a good fit to many well-known, psychoacoustic intensity discrimination data. They also show that the exponent in this alternative model must be nonconstant with the discrimination criterion in experiments implementing this averaging of data.