When something is repeated often, we tend to remember it better. But a new study published in Psychological Science has found that we may also mistakenly believe that repeated experiences happened longer ago than they actually did. Across six experiments involving hundreds of adults, researchers found that when an image or piece of information was presented multiple times, people consistently judged its first appearance as being further in the past than it really was. This illusion of time—called the “temporal repetition effect”—was surprisingly strong, distorting people’s memory of when something happened by as much as 25 percent.
This finding challenges a long-held assumption in psychology: that the vividness or strength of a memory helps us gauge how recently something happened. According to this idea, if a memory feels faint or unclear, we assume it happened a long time ago. If it feels fresh and clear, we assume it was more recent. But the results of this study suggest that things we remember well—precisely because they were repeated—might actually seem older in our memory.
The researchers were inspired by everyday experiences. “We all know what it is like to be bombarded with the same headline day after day after day. We wondered whether this constant repetition of information was distorting our mental timelines,” said study author Sami Yousif, who will be an assistant professors at The Ohio State University after August 1.
Even if that headline first appeared just a few days ago, it might begin to feel like it happened weeks ago simply because of how often it has been repeated. This intuition led the researchers to ask whether repetition itself could create a distortion in how far back in time we think something happened.
To explore this idea, Yousif and his co-author — Brynn E. Sherman — conducted a series of experiments using object images and online memory tasks. In the first experiment, 50 participants viewed a sequence of images of everyday objects, such as a stapler or a watering can. Some images were shown only once, while others were repeated across five blocks of trials. After viewing the sequence, participants were shown the same images again and asked to indicate when in the experiment they had first seen each one. They did this by moving a marker along a visual timeline.
The key design of the experiment allowed for a direct comparison: each repeated image was paired with a non-repeated image that had been shown right before it in the original sequence. This meant that both images were originally seen at nearly the same time. But despite this, participants consistently remembered the repeated images as having occurred earlier. This illusion remained strong even when participants successfully recognized the images, suggesting that memory accuracy for the items themselves wasn’t driving the effect.
The researchers also found that the more times an image was repeated, the stronger the illusion became. Images shown five times were remembered as having occurred even further back than those shown only two or three times. This pattern persisted across all seven sets of image conditions.
“We were surprised at how strong the effects were,” Yousif told PsyPost. “We had a hunch that repetition might distort temporal memory, but we did not expect these distortions to be so significant.”
To test whether this illusion was due to memory strategies or shortcuts—such as participants assuming that anything repeated must have come earlier—the researchers ran a follow-up version of the experiment with added survey questions. Participants were asked to describe their strategies and to estimate how often they relied on repetition when placing images in time. Although some participants reported using such strategies, these responses did not predict the strength of the illusion. That means the effect likely wasn’t the result of deliberate reasoning, but rather something deeper in how memory and time perception interact.
Another experiment ruled out the possibility that pauses between blocks of images, which might signal shifts in context or time, were responsible for the effect. When participants viewed the same kinds of repeated images without any breaks between blocks, the illusion remained just as strong.
A third experiment tested whether the illusion would still appear if people were told ahead of time that they would be asked to judge the timing of each image’s first appearance. Even when participants were explicitly warned to focus on when they saw an image for the first time, the repetition still caused them to misjudge when that first exposure occurred.
In a fourth experiment, the researchers had participants indicate during the viewing phase whether each image was “new” or “old” each time it appeared. This allowed the team to track which repetitions participants actually remembered. Again, the illusion held: the more times people remembered seeing an image, the more likely they were to place its first appearance earlier in time. A statistical analysis showed that it wasn’t just the number of times an image was shown, but the number of times it was remembered that mattered most.
To strengthen their results, the researchers changed the format in a fifth experiment. Instead of using a timeline, they showed participants two images—one repeated, one not—and asked which one they saw first. Even though the non-repeated image had always come first, participants chose the repeated image as having come first nearly 80 percent of the time.
Finally, in a sixth experiment, the team tested whether this effect held up over a longer period. Participants viewed image sequences across five days and returned three days later to complete the memory test. Even with this extended timeline, people continued to remember repeated images as having occurred earlier. This finding suggests that the illusion isn’t just a short-term quirk, but a lasting feature of memory that may shape how we recall events across days or even weeks.
This new research sheds light on a puzzling phenomenon: our sense of time doesn’t always match the calendar. The feeling that something happened “ages ago” may not be a reliable indicator of when it truly occurred, especially if that something was repeated many times. The study also highlights a gap in current memory theories. Many psychological models assume that stronger memories are perceived as more recent, but these results show the opposite.
“People should take away two things: (1) Time perception is illusory. That is, our sense of when things occurred is systematically distorted in predictable ways. (2) These distortions can be substantial, even if their causes are simple (i.e., the mere repetition of information),” Yousif said.
There are several possible reasons why this illusion happens, according to the researchers. One idea is that when an item is repeated, later presentations may “remind” us of the earlier ones, effectively reinforcing the memory of the first appearance and embedding it more deeply. Over time, this could make the initial event feel like it happened further in the past. Another idea is that our sense of when something happened is not stored directly in memory, but is instead reconstructed using cues such as repetition. In that case, repetition could trick us into thinking an event happened longer ago than it really did.
As with all research, there are some limitations. All the participants were English-speaking adults living in the United States, so the results may not apply to all cultures or age groups. And although the experiments were designed to mimic real-world memory experiences, they still took place in a controlled digital environment using images of objects, not complex or emotionally charged events.
Still, the researchers emphasized the consistency of the findings across different experimental designs. “We tested the phenomenon in a variety of different ways, and it was incredibly robust in all of those cases,” Yousif said. “This strikes us as a particularly strong effect.”
The researchers hope that future work will explore how this illusion affects different types of memories—like emotional events, social interactions, or news stories—and how it might influence decision-making, planning, and even public opinion. They also suggest studying whether the effect operates differently in children, older adults, or people with memory impairments.
“We remain interested in time perception at the scale of ordinary experience,” Yousif explained. “In other words, we really want to know what other factors influence how our mental timelines are shaped by our experience.”
The study, “An Illusion of Time Caused by Repeated Experience,” was published online on April 18, 2025.
