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ABSTRACT: This article revisits two classical issues in experimental methodology: experimenter bias and demand characteristics. We report a content analysis of the method section of experiments reported in two psychology journals (Psychological Science and the Journal of Personality and Social Psychology), focusing on aspects of the procedure associated with these two phenomena, such as mention of the presence of the experimenter, suspicion probing, and handling of deception. We note that such information is very often absent, which prevents observers from gauging the extent to which such factors influence the results. We consider the reasons that may explain this omission, including the automatization of psychology experiments, the evolution of research topics, and, most important, a view of research participants as passive receptacles of stimuli. Using a situated social cognition perspective, we emphasize the importance of integrating the social context of experiments in the explanation of psychological phenomena. We illustrate this argument via a controversy on stereotype-based behavioral priming effects.
Perspectives on Psychological Science 11/2012; 7(6):572–584. · 4.89 Impact Factor
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ABSTRACT: Examine the influence of altering the size of snack food (ie, small vs large cookies) on short-term energy intake.
First- and sixth-graders (n = 77) participated in a between-subjects experimental design. All participants were offered the same gram weight of cookies during an afternoon tea at their school. For half of the participants, food was cut in 2 to make the small item size. Food intake (number of cookies, gram weight, and energy intake) was examined using ANOVA.
Decreasing the item size of food led to a decrease of 25% in gram weight intake, corresponding to 68 kcal. Appetitive ratings and subject and food characteristics had no moderating effect.
Reducing the item size of food could prove a useful dietary prevention strategy based on decreased consumption, aimed at countering obesity-promoting eating behaviors favored by the easy availability of large food portions.
Journal of nutrition education and behavior 03/2012; 44(3):251-5. · 1.36 Impact Factor
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ABSTRACT: While larger containers have been found to increase food intake, it is unclear whether this effect is driven by container size, portion size, or their combination, as these variables are usually confounded. The study was advertised as examining the effects of snack food consumption on information processing and participants were served M&M's for free consumption in individual cubicles while watching a TV show. Participants were served (1) a medium portion of M&M's in a small (n=30) or (2) in a large container (n=29), or (3) a large portion in a large container (n=29). The larger container increased intake by 129% (199 kcal) despite holding portion size constant, while controlling for different confounding variables. This research suggests that larger containers stimulate food intake over and above their impact on portion size.
Appetite 01/2012; 58(3):814-7. · 2.59 Impact Factor
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ABSTRACT: The perspective that behavior is often driven by unconscious determinants has become widespread in social psychology. Bargh, Chen, and Burrows' (1996) famous study, in which participants unwittingly exposed to the stereotype of age walked slower when exiting the laboratory, was instrumental in defining this perspective. Here, we present two experiments aimed at replicating the original study. Despite the use of automated timing methods and a larger sample, our first experiment failed to show priming. Our second experiment was aimed at manipulating the beliefs of the experimenters: Half were led to think that participants would walk slower when primed congruently, and the other half was led to expect the opposite. Strikingly, we obtained a walking speed effect, but only when experimenters believed participants would indeed walk slower. This suggests that both priming and experimenters' expectations are instrumental in explaining the walking speed effect. Further, debriefing was suggestive of awareness of the primes. We conclude that unconscious behavioral priming is real, while real, involves mechanisms different from those typically assumed to cause the effect.
PLoS ONE 01/2012; 7(1):e29081. · 4.09 Impact Factor
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ABSTRACT: Studies considering the impact of food-size variations on consumption have predominantly focused on portion size, whereas very little research has investigated variations in food-item size, especially at snacking occasions, and results have been contradictory. This study evaluated the effect of altering the size of food items (ie, small vs large candies) of equal-size food portions on short-term energy intake while snacking. The study used a between-subjects design (n=33) in a randomized experiment conducted in spring 2008. In a psychology laboratory (separate cubicles), participants (undergraduate psychology students, 29 of 33 female, mean age 20.3±2 years, mean body mass index 21.7±3.7) were offered unlimited consumption of candies while participating in an unrelated computerized experiment. For half of the subjects, items were cut in two to make the small food-item size. Food intake (weight in grams, kilocalories, and number of food items) was examined using analysis of variance. Results showed that decreasing the item size of candies led participants to decrease by half their gram weight intake, resulting in an energy intake decrease of 60 kcal compared to the other group. Appetite ratings and subject and food characteristics had no moderating effect. A cognitive bias could explain why people tend to consider that one unit of food (eg, 10 candies) is the appropriate amount to consume, regardless of the size of the food items in the unit. This study suggests a simple dietary strategy, decreasing food-item size without having to alter the portion size offered, may reduce energy intake at snacking occasions.
Journal of the American Dietetic Association 05/2011; 111(5):727-31. · 3.59 Impact Factor
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ABSTRACT: According to Unconscious Thought Theory (UTT: Dijksterhuis \& Nordgren, 2006), complex decisions are best made after a period of distraction assumed to elicit ``unconscious thought''. Over three studies, respectively offering a conceptual, an identical and a methodologically improved replication of Dijksterhuis et al.\ (2006), we reassessed UTT's predictions and dissected the decision task used to demonstrate these predictions. We failed to find any evidence for the benefits of unconscious decision-making. By contrast, we found some evidence that conscious deliberation can lead to better decisions. Further, we identified methodological weaknesses in the UTT decision task: (a) attributes weighting was neglected although attributes were seen as different in importance; (b) the material was not properly counterbalanced; and (c) there was some confusion in the experimental instructions. We propose methodological improvements that address these concerns.
Judgment and decision making 01/2009; 4(7):601-610. · 2.62 Impact Factor
