Ever shared a post only to realize later it was fake news? You’re not alone, and psychology explains why. The “sleeper effect,” a phenomenon where a message’s influence grows over time as its source fades from memory, has gained new relevance in the age of social media misinformation. A foundational 2004 meta-analysis by Kumkale and Albarracín unpacks the mechanics of sleeper effects in persuasion.  (and who doesn’t love a meta study?), while a 2023 study by Ruggieri et al. examines how this effect applies to fake news about COVID-19 workplace safety. Together, these studies reveal why false claims stick in our minds and what makes them so hard to correct.

Methodology

Kumkale and Albarracín (2004)

This meta-analysis compiled data from 72 experiments to examine the sleeper effect across multiple contexts. The study investigated conditions influencing delayed persuasion, including the timing of discounting cues and the audience’s ability and motivation to process messages. The researchers analyzed the persistence of message impact when the source’s credibility faded from memory, thus isolating key factors that contribute to the sleeper effect.

Ruggieri et al. (2023)

This study involved 324 Italian white-collar workers who viewed Facebook posts about COVID-19 workplace safety. Participants were exposed to three types of posts: real news, real news with a discounting cue, and fake news. Researchers measured participants’ perceptions immediately and one week later, focusing on memory recall and belief in the information. They categorized participants as either “believers” or “nonbelievers” of the fake news to analyze differences in perception and memory retention over time.

Findings

Kumkale and Albarracín (2004)

The meta-analysis confirmed the sleeper effect’s occurrence under specific conditions: when discounting cues followed persuasive arguments and when recipients had high motivation or ability to process the message. Persuasion increased over time as memory of the noncredible source decayed. The review emphasized the importance of the timing of discounting cues and the cognitive engagement of the audience, suggesting that motivated audiences are more susceptible to the sleeper effect.

Ruggieri et al. (2023)

Participants remembered fake news better than real news, even when they initially recognized it as false. Fake news is often more emotionally provocative, novel, or sensational, making it more memorable. The study also posits that the narrative structure and vividness of fake news stories can enhance recall.  In the end, memory of the message persisted, but memory of the source diminished over time, suggesting a sleeper effect. Those who initially believed the fake news maintained or increased their positive impression of the content over time. Conversely, nonbelievers showed a slight increase in acceptance but to a lesser extent. The study highlights how fake news influences perception long after the source is forgotten.

Critiques of the Research or Additional Areas of Potential Study

Kumkale and Albarracín (2004)
The meta-analysis provides robust evidence for the sleeper effect but relies on aggregated data from diverse studies with varying methodologies. As with all meta studies, the lack of uniformity across experiments presents a challenge in isolating causal mechanisms. Further research should explore real-world applications (as in Ruggieri), such as political messaging or health communication, to test the sleeper effect outside controlled environments. Investigating long-term behavioral changes could also deepen understanding of its societal impact.

Additionally, the meta study was published in 2004 –  predating social media’s rise.

Ruggieri et al. (2023)
The study effectively demonstrates the sleeper effect in the context of workplace safety perceptions but is limited by its sample of educated white-collar workers.  In addition, Ruggieri’s study tested memory after one week—what happens after months?  Future research should explore different demographic groups to determine if educational background affects susceptibility to misinformation.   Future research should explore media diets to determine if media mode affects the sleeper effect.  Memes and now deepfake pictures or video are likely to stick around a lot more than a text based message. Additionally, the study focuses on COVID-19-related content, which may limit generalizability due to potential confounding factors. Examining other controversial topics could provide a broader understanding of the sleeper effect’s impact.   I may as so bold as to suggest UFO’s?

Comparative Analysis
Kumkale and Albarracín offer a foundational, theoretical perspective on the sleeper effect, establishing cognitive mechanisms and general conditions for delayed persuasion.
In contrast, Ruggieri et al. apply these principles to a specific real-world context, highlighting how emotionally charged and vivid fake news influences memory. The former provides broad insights into persuasion dynamics, while the latter demonstrates practical implications in digital misinformation.  Future studies should integrate both approaches, combining theoretical rigor with real-world relevance to better understand and combat misinformation.

Neither study offers much on how to combat the sleeper effect, merely suggest implications for countering misinformation. Kumkale and Albarracín (2004) highlight the importance of disrupting the dissociation process by ensuring the credibility of the source remains linked to the message. Ruggieri et al. (2023) imply that repeated corrections and reminders of the source’s noncredibility could mitigate the sleeper effect. Future research should explore these mitigation strategies more systematically, particularly in digital environments where misinformation spreads rapidly.

Conclusion: Why This Matters

The sleeper effect isn’t just an academic curiosity—it’s a weapon in the misinformation playbook.

Kumkale and Albarracín (2004) provide a theoretical framework for the sleeper effect, showing its occurrence when discounting cues follow persuasive arguments and when audiences engage cognitively. Their meta-analysis emphasizes cognitive mechanisms and general conditions for delayed persuasion.

Ruggieri et al. (2023) apply this framework to real-world misinformation about COVID-19, revealing that fake news persists in memory even when initially identified as false. Their findings demonstrate how emotional and vivid content enhances recall, highlighting practical implications in the context of social media.

In a world barrelling towards deep fakes, and where where misinformation spreads faster than facts, understanding the sleeper effect isn’t just smart—it’s survival!