Citizen science is a method of generating new scientific knowledge outside the bounds of traditional research institutions and contexts, which take a variety of different forms and engage the public in numerous formats, activities, and stages in the research process (Pateman et al., 2020; WeObserve Consortium, 2021). One important type of citizen science is a participatory research method in which members of the general public are trained to collect data, which expands data collection efforts to a larger scale and broader array of contexts than would be possible for researchers alone due to practical limitations of time and resources (Ebitu et al., 2021). Another important benefit is that it allows data collection in contexts that are typically inaccessible to researchers (Pollard et al., 2017). Participating in citizen science impacts scientific knowledge (Bonney et al., 2009, 2016; Brossard et al., 2005; Shirk et al., 2012) as well as participants’ attitudes and behaviors (Hajibayova et al., 2021; Price and Lee, 2013; Severin et al., 2023). Citizen science on environmental and natural resource topics has been found to positively impact conservation attitudes and behavior (Chase and Levine, 2018; Severin et al., 2023).

Quantification of household food waste has been identified as a key knowledge gap (Movilla-Pateiro et al., 2021), with citizen science being a valuable research methodology to better fill this gap in knowledge (Fritz et al., 2019). Additionally, citizen science has been recognized as a methodology to reduce food waste, as the process of quantifying waste could lead citizen scientists to alter their behavior (Pateman et al., 2020; Pelt et al., 2020). Indeed, one of the key impacts of citizen science on household food waste is the participants’ increased awareness of waste (Pelt et al., 2020). Household food waste citizen science studies utilize a variety of methods, including diaries, separating food waste from other trash for waste audits (Wenlock et al., 1980), taking pictures (Farr-Wharton et al., 2014), and self-report surveys (Graham-Rowe et al., 2015). Of these methods, dairies have been identified as a method that has a high burden of time and effort for participants, which can lead to high dropout rates (Langley et al., 2010). However, it has been noted that the use of diaries to record food waste can lead to changes in waste behavior (Langley et al., 2010) because it is a cue that focuses participants’ attention on food waste (Sharp et al., 2010).

Roe et al. (2022) conducted a randomized controlled trial study in which individuals were enrolled in an intervention that included the use of a phone app that would allow participants to take pictures and quantify their waste, as well as sessions with a trained coach to help participants learn about methods to reduce food waste and develop individualized food waste reduction goals, as well as receiving follow-up communications via text, email, or phone on additional tips to reduce food waste (Roe et al., 2022). While not formally presented as a citizen science study, this study was similar to our study, in that it involved participants recording data on their food waste and collecting information to assess waste patterns. However, in addition to quantification methods, the Roe et al. (2022) study included an associated intervention with the intention of reducing food waste. In contrast, our current study aimed to determine whether the training required for data collection, the data collection process, and the reporting process were sufficient to significantly change participants’ attitudes and behaviors towards food waste. We hypothesized that participating in the training and daily data collection required for the citizen science project would influence participants’ knowledge, attitudes, and beliefs about food waste, ultimately promoting long-term reduction in household food waste behavior.

While there is existing citizen science research on food waste, such as the study by Roe et al. (2022), which included both data collection and a waste reduction intervention, research is lacking on how citizen scientists’ knowledge, attitudes, beliefs, and behaviors related to food waste are impacted by data collection. Previous studies have called attention to the importance of examining how citizen science impacts behavior (Pateman et al., 2020), and existing research has examined the reasons that people participate in citizen science related to food waste (Florença et al., 2025), or the relationships between citizen scientists’ attitudes and their food waste (Pierini et al., 2021). However, our study differs from prior work in that we empirically test whether participation in citizen science alone—absent a formal intervention—produces changes in food-waste-related attitudes, beliefs, and behaviors. If participating in citizen science research on household food waste can benefit participants and communities, then effectively be used in the future as an intervention to help support the reduction of household food waste.

Originating in social psychology, Theory of Planned Behavior (TPB) explains how beliefs, attitudes, subjective norms and perceived behavioral control shape behavioral intentions and actions. According to TPB, an individual’s behavior is shaped by their positive or negative attitudes about the behavior, their subjective norms about the behavior (their assessment of social pressure about the behavior from people who are important to them), and their perceived behavioral control related to performing the behavior (the confidence that they have about whether they are able to do the target action, given internal and external constraints or supports) (Fishbein and Ajzen, 1977). For the last half century, TPB has been widely used to study behavior in public health, environmental studies, and consumer behavior. TPB is frequently used to study environmental behavior, such as water conservation (Trumbo and O’Keefe, 2001), energy consumption (Sparks et al., 2014), recycling (Boldero, 1995; Taylor and Todd, 1995), and sustainable food choices (Han and Hansen, 2012). TPB is the dominant framework for examining household food waste (Schanes et al., 2018), making it an appropriate theoretical lens for our study.

In this study, we used TPB as the evaluative framework for assessing whether participation in a household food waste citizen science project is associated with changes in key psychosocial determinants of behavior. Specifically, TPB guided the selection of survey constructs used to measure changes in attitudes, behavioral beliefs, subjective norms, and perceived behavioral control related to reducing household food waste. Rather than testing predictive relationships among TPB constructs, this study uses TPB to examine whether and how participation in citizen science is associated with shifts in these determinants over time.

Hence, the objective of this study is to determine whether participation in a citizen science project focused on household food waste is associated with changes in participants’ psychosocial determinants of behavior and self-reported waste-related practices. Guided by TPB, we use a paired pre- and post-program evaluation to examine changes in attitudes, behavioral beliefs, subjective norms, perceived behavioral control, and reported behaviors related to reducing household food waste. By evaluating citizen science as both a data collection approach and a potential behavior-change intervention, this research contributes evidence on how participatory measurement may support the broader goals of reducing household food waste and promoting sustainability.

Participants received a pre-program survey with questions about perceptions, attitudes, and beliefs about household food waste based on TPB constructs. The pre-program survey also contained demographic questions. Six months after the program, participants received a post-program survey containing the same questions about food waste based on TPB constructs, along with questions about how they perceived that the program impacted their attitudes and behavior. Both surveys were distributed via Qualtrics.

Program participants’ attitudes about household food waste were measured using a 5-point semantic differential scale (e.g., 1 = Harmful, 5 = Beneficial; 1 = Not a priority, 5 = High priority). Participants were asked six questions about their behavioral beliefs. These included whether they believed that reducing household food waste would conserve energy or water, reduce food insecurity, decrease landfill use or greenhouse gas emissions, and make a meaningful environmental difference. We also included questions to assess both their subjective norms and their normative beliefs, such as whether the people who are important to them support their efforts to reduce household food waste, and whether the media they consume emphasizes the significance of reducing food waste. To assess their perceived behavioral control, participants were asked whether they believe it would be possible for them to discard less food and whether they feel that reducing food waste is within their control. They were also asked 6 questions to assess their beliefs about reducing household food waste. The post program survey was distributed in October 2024. The survey asked participants whether they had changed their attitudes, beliefs or behaviors as a result of participating in the citizen science study, including whether they had increased awareness of food waste or the importance of composting, and whether they changed behavior, including adopting new behavior to support environmental sustainability and reduce food waste. Participants answered Likert-type questions about their beliefs, subjective norms, perceived behavioral control, and the post program reflection questions. On the post program survey, participants were prompted to provide open-ended responses describing how the program impacted their lives.

We used SPSS to analyze the quantitative data. We calculated descriptive statistics for program participants’ demographics. We tested the internal reliability for the seven items making up the household food waste attitudes scale using Cronbach’s alpha, which showed a high degree of reliability (α = 0.88). To assess the change in program participants, we compared the means of paired pre-and post-test data. We used Shapiro–Wilk tests to assess the normality of the data (Shapiro and Wilk, 1965). Because data were not normally distributed, we employed nonparametric methods. We compared the means of paired observations before and after the program with the two-sided Wilcoxon signed-rank test (p < 0.05). The open-ended responses were thematically coded using an inductive-deductive approach coding anticipated responses and emergent themes (Saldaña and Omasta, 2022).

Our study did not have a control group; therefore, we cannot rule out the possibility that external factors influenced our findings. While our study achieved a high response rate, we were unable to assess response bias for citizen scientists who did not complete the post-program survey. The sample is not representative of the general population, and research is needed to assess the impact of citizen science on individuals who are less affluent, have lower levels of formal education, or do not already have high interest in science or positive attitudes toward reducing food waste, as has been previously recommended (Chase and Levine, 2018; Pateman et al., 2021). Respondent gender was not collected in this study in order to minimize participant burden and because it was not expected to meaningfully influence the study’s primary outcomes, which focused on changes in psychosocial constructs and household-level food waste reporting associated with citizen science participation. Given the already extensive data collection requirements, additional demographic measures were intentionally limited, and inclusion of respondent gender risked introducing interpretive ambiguity without clear analytical benefit.

Future research could examine whether different types of data collection approaches have varying impacts on participants. For example, our data collection methodology was onerous on participants, requiring them to record several pages of data each day, then to transfer that data to the online survey platform for the research team, a process that took participants an average of 50 min to complete. It is worth assessing whether simplified data collection processes, such as by using electronic methods for data collection, such as using an app or allowing participants to submit pictures, would have similar positive effects on participants’ food waste knowledge, attitudes, beliefs, and behaviors without imposing as much of a burden on their time. Just as different methods of collecting and reporting data may have differing impacts on participants, future studies could assess whether the extent of participation and the rigor of data collection and reporting impact the magnitude of change in attitudes and behaviors of citizen scientists. Additional qualitative data from interviews or focus groups of participants could also help illuminate participants’ experiences with the citizen science process or their perspectives on household food waste and the factors that contribute to it. Finally, all measures of attitudes, beliefs, and behaviors relied on self-report, which may introduce social desirability bias.