A systematic review and meta-analysis of the effectiveness of nudging to increase fruit and vegetable choice.

Background: Nudging refers to interventions that organize the choice architecture in order to alter people's behaviour in a predictable way without forbidding any options or significantly changing their economic incentives. As a strategy to encourage healthy behaviour, nudging can serve as a complement to health education. However, the empirical evidence regarding the effectiveness of nudging as a way to influence food choice remains contradictory. To address this issue, a systematic review and meta-analysis was conducted to test the effects of nudging to encourage people to select more fruit and vegetables. Methods: A systematic literature search was performed on PubMed, Medline, PsycInfo, Cochrane library, Scopus and Google Scholar. After quality assessment, 20 articles (23 studies) were retained for narrative synthesis. Twelve articles (14 studies) contained enough information to calculate effect-sizes for meta-analysis using Comprehensive Meta-analysis software. Results: The meta-analysis shows that nudging interventions that aim to increase fruit and/or vegetable choice/sales/servings have a moderately significant effect (d = 0.30), with the largest effect for altering placement (d = 0.39) and combined nudges (d = 0.28). Conclusion: The results of this review provide an indication of the effectiveness of nudging on fruit and vegetable choice in terms of actual effect-sizes, while also highlighting the problems that must be addressed before more definitive conclusions can be drawn.

Individual and situational determinants of plastic waste sorting: an experience sampling method study protocol.

BACKGROUND: Plastic waste management is one of the most challenging problems of our time. Until now, only 9% of the produced plastics has been recycled. In order to increase recycling, a behavior change towards sorting of plastic waste is needed. Therefore, the main aim of the study is to gain insight in the individual and situational determinants associated with plastic waste sorting behavior. The Integrated Framework for Encouraging Pro-environmental Behaviour will be used as the theoretical framework. This framework assumes that individual egoistic and hedonic values are negatively related to pro-environmental behaviour, whereas individual biospheric and altruistic values are positively related to pro-environmental behaviour. Situational cues can activate these values, resulting in (non) pro-environmental behaviour. Taking the Integrated Framework for Encouraging Pro-environmental Behaviour into account, this study will test the hypothesized associations between individual and situational determinants and plastic waste sorting behavior, using an ecological momentary assessment approach (Experience Sampling Method, ESM). METHODS: A signal-contingent scheme with semi-random intervals will be used for the ESM questionnaire. Over a period of seven consecutive days, an ESM-based smartphone app will prompt participants ten times a day to fill in a short questionnaire containing questions about situational determinants and plastic waste sorting behaviour. Participants will also complete an online questionnaire before and after the study measuring the individual determinants and plastic waste sorting behaviour. DISCUSSION: ESM has many benefits over traditional surveys, such as improved ecological validity and the possibility to explore temporal relationships. The disadvantages of ESM are mainly related to the burden for the participants and the possibility of reactivity effects. The results will provide insight into the relationship between situational cues, individual values and plastic waste behaviour. The practical implications of the findings of this study can be of interest for policy makers in order to reach plastic waste reduction targets. Furthermore, the situational cues that activate values, which increase or decrease plastic waste sorting, can be targeted in interventions. The results of this study can also be relevant for further research studying and stimulating pro-environmental behaviour in general.

Effects of prebiotics on affect and cognition in human intervention studies.

Studies conducted in rodents have highlighted that neurobiological processes underlying cognition and affect are modulated by the gut microbiota. Certain dietary fibers are able to modulate the composition of gut microbiota and are thus considered prebiotics. A review of the impact of the available prebiotic intervention studies in humans on cognition and affect, addressing the potential mediating role of the microbiota, was conducted. PubMed, Scopus, and PsycINFO were selected as sources. Fourteen articles were eligible for narrative synthesis. Data extraction and quality assessment were performed with characteristics established a priori. Some chronic prebiotic interventions (>28 d) improved affect and verbal episodic memory compared with a placebo. Acute prebiotic interventions (<24 h) were more efficient in improving cognitive variables (eg, verbal episodic memory). Future research should measure microbiota using adequate methodologies and recruit patients with dysbiosis, inflammation, or psychopathology. More research is needed to unravel the conditions required to obtain effects on affect and cognition.