New psychology research reveals how repetitive thinking primes involuntary memories

New research provides evidence that the repetitive thoughts occupying a person’s mind can directly influence the spontaneous memories they experience later. This phenomenon, termed “preoccupation priming,” suggests that focusing on a specific topic creates a tendency for the brain to retrieve personal memories related to that subject. The study was published in the scientific journal Consciousness and Cognition.

Psychologists have studied involuntary autobiographical memories for many years. These are memories of past personal events that pop into consciousness without any deliberate attempt to retrieve them. They often occur during mundane activities, such as walking down the street or washing dishes.

Previous research indicated a strong connection between a person’s current life concerns and the content of these spontaneous memories. For instance, diary studies showed that individuals going through a breakup or starting a new diet often reported involuntary memories centered on those specific themes.

However, these earlier studies were primarily correlational. They relied on participants recording their daily experiences, which made it difficult to determine the direction of cause and effect. It was unclear if thinking about a topic caused the memories, or if having the memories caused the person to think about the topic more frequently.

Researchers John H. Mace and Emily Chow sought to resolve this ambiguity by conducting a controlled laboratory experiment. They aimed to establish a causal link by manipulating what participants thought about and then measuring the subsequent effect on their involuntary memories. The goal was to demonstrate that the cognitive act of repetitive thinking serves as a mechanism that primes the memory system.

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The study included 60 undergraduate students as participants. The researchers randomly assigned these individuals to one of two groups: a repetitive thinking group and a control group.

The experiment began with a priming phase designed to simulate the experience of being preoccupied. Participants were told they were taking part in a study on concentration. They viewed a series of slides on a computer screen that instructed them to imagine an activity or think about a specific topic.

In the repetitive thinking group, participants viewed ten slides. Seven of these slides instructed them to “think about food.” The remaining three slides offered unrelated instructions, such as imagining raking leaves or setting goals. Each slide remained on the screen for 35 seconds, forcing the participant to maintain their focus on the topic for a sustained period.

The control group also viewed ten slides with similar timing. However, only one slide instructed them to think about food. The other nine slides featured various unrelated prompts, such as imagining sitting in a chair, thinking about rain, or thinking about watches. This design ensured that the control group was exposed to the topic of food but did not engage in the repetitive rumination characteristic of a preoccupation.

Following the priming phase, the researchers administered a vigilance task. This is a standard method used in psychology to elicit and record involuntary memories. Participants watched a sequence of 92 slides. Each slide contained a pattern of horizontal or vertical lines with a short phrase embedded in the center, such as “hanging your clothes” or “growing a garden.”

The participants were given a simple, repetitive assignment to keep them occupied. They had to say “yes” out loud whenever they saw a slide with vertical lines. This type of low-attention task is known to encourage mind-wandering, which facilitates the emergence of spontaneous memories.

The researchers instructed the participants to ignore the text phrases on the slides but to pay attention to their own mental states. If they experienced a spontaneous thought or a specific memory during the task, they were to click a mouse button and write down what they experienced in a booklet.

Crucially, the vigilance task included specific cues designed to trigger food-related memories. Of the 89 non-practice slides, seven contained phrases directly related to food, such as “buying food,” “cooking dinner,” or “eating good food.” The remaining 82 slides contained neutral phrases unrelated to the priming topic.

After the task was completed, the participants reviewed their written entries. They categorized each entry as either a general thought or a specific memory. Two independent judges also reviewed the entries to determine if they were related to food.

The researchers found that the participants who engaged in repetitive thinking about food produced significantly more involuntary memories related to food than the control group. This outcome supports the hypothesis that preoccupation operates as a form of priming. By thinking about a subject repeatedly, the brain becomes sensitized to that information, making related past experiences more accessible to involuntary retrieval.

The study yielded another finding regarding the total number of memories produced. The repetitive thinking group reported a higher number of involuntary memories overall, regardless of whether the memories were about food. This suggests that the act of repetitive thinking might trigger a state of heightened memory accessibility.

The researchers suggest this increase in total memories may be due to “collateral priming.” This concept implies that when a specific network of memories is activated, such as memories about food, the activation spreads to other associated memories. For example, a memory about a dinner party might activate memories about the friends who were there or the location where it happened, even if those details are not strictly about food.

The study also compared the number of spontaneous thoughts that were not memories. The data showed no significant difference between the two groups regarding these non-memory thoughts. This indicates that the priming effect was specific to the autobiographical memory system and did not simply increase general thoughts about the topic.

These findings have implications for understanding how our daily mental habits shape our cognitive reality. The results suggest that the things we obsess over or worry about do more than just occupy our conscious attention. They actively recruit our past experiences, bringing related memories to the forefront of our minds.

“Your daily involuntary memories will track your thoughts and all the information that you process,” explained Mace, professor and chair of the Department of Psychology at Eastern Illinois University. “Most of the time, you will be unaware of the connection. If you a preoccupied with a particular idea (e.g., losing weight, a former partner), thinking about it a lot, this will influence your involuntary memories, in that many of them will feature the topic you are preoccupied with. You will make these connections, and this will not be a problem unless the preoccupations and memories are distressing.”

There are some limitations to this study that should be considered. The experiment focused on a single topic: food. While food is a common subject of daily thought, it is possible that other topics might yield different results.

Additionally, the duration of the repetitive thinking in the lab was relatively short, totaling about four minutes. Real-world preoccupations often last for days, weeks, or months. It is plausible that the effects observed in the laboratory would be even stronger in a natural setting where the repetition is more frequent and intense.

Future research in this area aims to explore different types of topics to see if the effect is universal. The scientists are also interested in examining how the frequency of the repetitive thought impacts the strength of the priming. Understanding these variables could provide deeper insight into how our internal monologues influence the way we remember our past.

The study, “Preoccupation priming: How repetitive thinking can influence our involuntary memories,” was authored by John H. Mace and Emily Chow.