Constructing bootstrap confidence intervals for principal component loadings in the presence of missing data: a multiple-imputation approach

Earlier research has shown that bootstrap confidence intervals from principal component loadings give a good coverage of the population loadings. However, this only applies to complete data. When data are incomplete, missing data have to be handled before analysing the data. Multiple imputation may be used for this purpose. The question is how bootstrap confidence intervals for principal component loadings should be corrected for multiply imputed data. In this paper, several solutions are proposed. Simulations show that the proposed corrections for multiply imputed data give a good coverage of the population loadings in various situations.     

Through the eyes of dieters: Biased size perception of food following tempting food primes

Why do some dieters succeed in controlling their diet while others do not? This research focused on a perceptual process—size perception of food objects—that may moderate the success of dieters in self-control dilemmas. We assessed successful and unsuccessful dieters' size perception of palatable food (Study 1) and diet-food (Study 2) after pre-exposing them to tempting food primes. Dieters perceived palatable food as bigger when primed with tempting food (vs. control prime), regardless of self-regulatory success in dieting (Study 1). Palatable food thus looms larger for both unsuccessful and successful dieters when in a “hot” state. In contrast, the perceived size of diet-food was increased by a tempting food prime only for successful dieters, but decreased for unsuccessful dieters (Study 2). These results are interpreted in terms of differences in the mental accessibility of competing goals (eating enjoyment vs. dieting) in successful vs. unsuccessful dieters. Indeed, when the dieting goal was made accessible for all dieters by a diet prime, even unsuccessful dieters perceived diet-food as bigger (Study 2). This research provides insight into a perceptual process that may be detrimental or beneficial in resolving self-control conflicts in the domain of eating and dieting behavior—and probably other domains of self-control as well.     

There is a fire burning in my heart: the role of causal attribution in affect transfer

The role of causal attribution in affect transfer of primes was addressed by examining the consequences of explicit evaluation of primes within the framework of the affect misattribution procedure (AMP; Payne, Cheng, Govorun, & Stewart, 2005). We reasoned that affect transfer occurs when primed affect remains diffuse and not bound to a specific object, hence capable of freely colouring subsequent evaluations of ambiguous objects. Accordingly, we propose that when people explicitly evaluate the prime, affect is clearly bound to the prime and becomes less capable of influencing subsequent judgements. Supporting this notion, affect transfer in the AMP was observed when participants ignored the primes, thereby keeping the primed affect relatively unbound. However, this effect disappeared when participants explicitly evaluated the primes before target stimuli were presented. Implications of these findings in determining how and when affect arising from one object carries over to another is discussed.     

As pleasure unfolds. Hedonic responses to tempting food

Why do chronic dieters often violate their dieting goals? One possibility is that they experience stronger hedonic responses to tempting food than normal eaters do. We scrutinized hedonic processing in dieters and normal eaters (a) by manipulating food preexposure and (b) by assessing both immediate and delayed hedonic responses to tempting food with an adapted affect-misattribution procedure. Without food preexposure, dieters showed less positive hedonic responses than normal eaters (Study 1). When preexposed to tempting-food stimuli, however, dieters exhibited more positive delayed hedonic responses than normal eaters (Studies 1 and 2). Furthermore, delayed hedonic responding was meaningfully related to self-reported power of food and state cravings (Study 2). These findings suggest that dieters experience difficulties in down-regulating hedonic affect when in a "hot" state and that self-regulation research may benefit from a greater emphasis on temporal dynamics rather than static differences.     

The efficacy of a brief internet-based self-help intervention for the bereaved

Research so far has shown little evidence that written disclosure facilitates recovery from bereavement. There are good reasons to assume that written disclosure may only benefit those bereaved who are at risk for developing problems or who are experiencing significant psychological problems as a result of their loss, and only when appropriate writing instructions are used. Drawing on previous work in the area of post-traumatic stress, a writing intervention was designed to test these assumptions. Bereaved individuals, who were still significantly distressed by their loss, were randomly assigned to the intervention condition (N = 460) or a waiting-list control condition (N = 297). Both groups filled in questionnaires online at baseline, and 3 and 6 months later. The intervention was administered via e-mail immediately after baseline measurement. Results showed that writing decreased feelings of emotional loneliness and increased positive mood, in part through its effect on rumination. However, writing did not affect grief or depressive symptoms. Contrary to expectations, effects did not depend on participants' risk profile or baseline distress level. Implications of these findings are discussed.     

Do-no-harm in coalition formation: Why losses inhibit exclusion and promote fairness cognitions

Previous research on coalition formation has established that people will not hesitate to exclude others in order to maximize their payoff. The authors propose that this view is too narrow and that the decision to exclude depends on the valence of the payoff. Consistent with a “do-no-harm” hypothesis, Experiment 1 showed that participants were more reluctant to exclude in order to minimize their losses than to maximize their gains. Experiment 2 replicated this effect and showed that participants were most affected by payoff valence when they were disposed to consider the viewpoint of others. Additional analyses revealed that participants were more motivated by fairness (Experiment 1) and that fairness was more cognitively accessible (Experiment 2) when payoffs were negative rather than positive.     

Scientific Realism in Action: Molecular Models and Boltzmann’s Bildtheorie

This paper approaches the scientific realism question from a naturalistic perspective. On the basis of a historical case study of the work of James Clerk Maxwell and Ludwig Boltzmann on the kinetic theory of gases, it shows that scientists’ views about the epistemological status of theories and models typically interact with their scientific results. Subsequently, the implications of this result for the current realism debate are analysed. The case study supports Giere’s moderately realist view of scientific models and theories, based on the notion of similarity, and it highlights the crucial role of model users. The paper concludes with a discussion of Boltzmann’s Bildtheorie, the sophisticated form of realism that he developed in response to the scientific problems of kinetic theory.     

CYBORG: MYTH OR REALITY?

Abstract. The idea of cyborg often is taken as a token for the distinction between human and machine having become irrelevant. In this essay I argue against that view. I critically analyze empirical arguments, theoretical reflections, and ultimate convictions that are supposed to support the idea. I show that empirical arguments at this time rather point in a different direction and that theoretical views behind it are at least questionable. I also show that the ultimate convictions presupposed deny basic tenets of traditional Christianity, while their claim to be based on science confuses scientific results with their interpretation on the basis of a naturalistic world‐view.     

Undermining trust and cooperation: The paradox of sanctioning systems in social dilemmas

Sanctioning systems in social dilemmas are often meant to increase trust in others and to increase cooperation. We argue, however, that sanctioning systems may also give people the idea that others act in their own self-interest and undermine the belief that others are internally motivated to cooperate. We developed the “Removing The Sanction” paradigm and a new trust manipulation, and showed in three experiments that when there is a sanction on defection, trust in others being internally motivated to cooperate is undermined: Participants who had experienced the presence of a sanctioning system trusted fellow group members less than participants who had not. In a similar vein, the sanction undermined cooperation when trust was initially high. The implications of these paradoxical findings are discussed.     

Breaking and creating habits on the working floor: A field-experiment on the power of implementation intentions

Previous research has shown that implementation intentions are effective tools to promote new behavior. The present study aimed to provide the first evidence that conscious planning is an effective tool in replacing well-learned habits with new habits. This was tested in a field-experiment on repetitive behavior in the domain of recycling, using 109 employees of a tele-company as participants. Recycling behavior of the participants was observed by the actual amount of paper and the number of plastic cups in their personal wastebaskets. Following a pre-measure, participants were assigned to either implementation intention conditions, conditions in which an eye-catching facility was placed to promote recycling behavior, or control conditions. Recycling behavior was substantially improved in the facility as well as the implementation intention conditions in week 1 and week 2 and still 2 months after the manipulation. These data supported our hypothesis that planning breaks down unwanted habits and creates new ones.