This study measures the value and progress of knowledge produced in marketing research by using meta-analytic effect sizes as a measure of scientific knowledge. The author combines the results of 176 meta-analyses that include data from more than 7,500 primary studies published between 1918 and 2012. The 1,841 meta-analytic effect sizes show that a considerable body of marketing knowledge has been developed, as expressed by a meta-meta-analytic correlation of .24. This medium-sized effect is as strong or stronger than effects that have been found in compilations of meta-analyses in other, more basic fields of inquiry (e.g., psychology), which shows that marketing is a successful academic discipline. The effect sizes vary across subject areas, with pricing showing the strongest effects, followed by consumer behavior; methods and new product development show the weakest effects. This finding reveals different degrees of knowledge production and varying benchmarks to assess the contribution of future research outcomes in these subject areas. Marketing knowledge follows a discontinuous model of progress: knowledge has increased over time, but at a decreasing rate; the marketing field, which is currently characterized by fragmentation and specialization, has reached a stage of maturity. The findings provide implications for further research regarding how to measure, evaluate, and progress knowledge in marketing.

Since the introduction of the persuasion knowledge model more than 25 years ago, many research studies have investigated how consumers’ persuasion knowledge affects their reactions to persuasion attempts. While most results have shown that persuasion knowledge increases coping responses and leads to less favorable evaluations of marketer actions, the findings vary considerably, leaving researchers with a limited understanding of the substance and structure of persuasion knowledge effects and the conditions that explain their variability. To develop a better understanding of persuasion knowledge effects in the marketplace, this study builds on the concept of persuasion to predict responses to marketers’ attempts to persuade consumers with different levels of persuasion knowledge. The study presents a meta‐analysis of the findings in 148 papers and 171 distinct data sets. Persuasion knowledge effects can be viewed as substantial compared with persuasion attempts, but persuasion knowledge cannot suppress or eliminate persuasion effects in the marketplace, as it only reaches around 50% of the explanatory power of persuasion. Persuasion knowledge effects on evaluations and coping depend on the characteristics of the persuasion process. All persuasion elements that help consumers identify and better understand benefits not just for themselves, but also for marketers and how marketers realize their benefits—such as the use of personal communication, communication about unfamiliar products or products with experience attributes, and receiver experience—lead to less favorable effects for marketers. This paper’s insights provide a new framework for persuasion knowledge effects in the marketplace, ideas for future research, and implications for researchers, consumers, policymakers, and marketers.

Despite firms’ emphasis on product visual aesthetics (PVA) for competitive advantage, questions remain regarding which aesthetic properties enhance PVA the most, the strength of PVA's effect on consumer responses, and moderating factors. To address these gaps, the authors conduct a meta-analysis of 727 effect sizes from 263 independent samples spanning 1993–2024. Findings reveal that both organizational and meaningful aesthetic properties positively impact PVA, and harmony is the strongest property. PVA positively influences both consumer attitudes and behaviors. The authors develop a comprehensive framework of moderators across five key groups: brand, product, communication, consumer, and environmental factors. The moderator analyses yield multiple important insights and (1) identify economic growth and consumption publicity as particularly influential, (2) recognize previously unexplored but relevant moderators (e.g., aesthetic object type, individualism, and income inequality), (3) clarify debated moderators (e.g., brand familiarity, product quality level, and gender), (4) reveal that certain moderator combinations can turn PVA effects negative (e.g., focusing on packaging aesthetics with utilitarian, private, nondurable, and low-quality products can turn the effect of PVA on attitudes negative), and (5) find an attitude–behavior gap in the moderating effects of PVA. The study provides new insights into the nuanced effects of PVA for effective application.

Abstract The use of social media influencers as persuasive marketing agents has become ubiquitous. However, a comprehensive understanding of their effectiveness, mechanisms, and moderation is still lacking. To address this gap, we conducted a meta-analysis of 71 papers, yielding 135 experimental studies and 571 effect sizes related to the impact of social media influencers compared to other forms of brand endorsements. Our results reveal that social media influencers significantly impact both consumer engagement and purchase intention, and they are relatively more effective than brand posts, virtual influencers, and celebrities. A meta-analytic structural equation model analyzing the influencing mechanisms suggests that social media influencers enhance consumer responses indirectly through their credibility and attractiveness. A meta-regression analysis further shows that various factors—including characteristics of the influencers, message, products, social media platforms, and followers, as well as their interaction with influencer size—moderate the effectiveness of social media influencers. Notably, our results indicate that influencer size can address some inconsistencies in previous research. For instance, small and medium-sized influencers are more effective in driving engagement, while larger influencers have greater impact on purchase intention. Our research provides novel, rich, and nuanced insights that can help managers with decisions such as: (a) when to choose influencers over alternatives, and (b) how to optimize their use.

Caffeine is the world's most popular stimulant and is consumed daily by a significant portion of the world's population through coffee, tea, soda, and energy drinks. Consumers often shop online and in physical stores immediately after or while consuming caffeine. This is further facilitated by the increasing prevalence of coffee shops and by the phenomenon of some retail stores having in-store coffee bars and offering complimentary caffeinated beverages. This research examines how caffeine consumption before shopping influences purchase behavior. The results of a series of experiments conducted in the field (at multiple retail stores across different countries) and in the lab show that consuming a caffeinated (vs. noncaffeinated) beverage before shopping enhances impulsivity in terms of more items purchased and higher spending. This effect is stronger for “high-hedonic” products and attenuated for “low-hedonic” products. These findings are important for managers to understand how a seemingly unrelated behavior (i.e., caffeine consumption) in and/or around the store affects spending. From a consumer perspective, although moderate amounts of caffeine consumption can have positive health benefits, there can be unintended negative financial consequences of caffeine intake on spending. Thus, consumers trying to control impulsive spending should avoid consuming caffeinated beverages before shopping.