We assume distant negative events remembered in detail must have been extreme

If I insisted on telling you about a recent meeting I'd endured at work, and I went into vivid detail about every misunderstanding and awkward moment, you'd probably infer that I'd had a fairly bad experience. Now imagine I told you about the same events with the same level of detail, but I was talking about a meeting that happened more than a year ago. Now you'd probably get the impression that I'd had a truly awful time. The reason, as reported recently in the Journal of Experimental Psychology: Applied, is that we tend to interpret negative events recounted in detail as being more serious, the longer ago that they happened.

Robert Smith and Norbert Schwarz began by asking a group of 133 undergraduates whose opinion they would value more when considering whether to try out a restaurant – someone who visited last week, or a year ago. Unsurprisingly, 99 per cent said they would put their faith in the recent visitor. In stage two of the study the researchers examined whether this hypothetical preference would pan out in practice.

They asked 164 adults to imagine that their out-of-town friend Dan had frequented a local restaurant when passing through, and then to read his review of the place, which he'd just written today. After reading the review, the participants said what they thought of the restaurant.

Crucially, some of the participants were told that Dan's restaurant visit had happened just a week ago, whereas others were told that it had happened one year ago – in both cases, there was an identical level of detail. Another variation was that some participants read a version of the review that was positive, others read a version that was scathing. When the review was scathing, participants formed a more negative opinion of the restaurant, just as you'd expect, but what was surprising was that their view was more negative when they thought the review was based on an experience that had happened one year ago rather than last week.

Smith and Schwarz predicted this would happen. A generally held (and broadly accurate) lay belief about memory is that over time, we tend to forget details, especially less important ones, therefore distant yet still well-recalled memories must be highly significant and reflect more extreme situations. So although it's reasonable to treat recent reviews as more reliable – after all, who knows if last year's cook is still employed – a detailed account of an old event comes across as more significant, like unearthing a Saxon sword intact and gleaming.

If this hypothesis is solid, you would expect the effect to melt away when an alternative explanation is available for the high level of detail, and that's exactly what the experimenters found: participants no longer showed a stronger response to Dan's negative memories of a one-year-old event when they were told that he has "near-photographic" memory.

Note that in both this experiment and another reported in the same article, older highly detailed recollections were only interpreted as having more significance when they were about a negative, as opposed to a positive, event. The researchers relate this to the general finding that "bad is stronger than good" – negative information signals problems and costs, giving us a stronger incentive to invest attention and reasoning.

The main finding about the power of distant and detailed negative memories has real-world implications. If a customer persists in broadcasting a complaint they feel wasn't adequately addressed, later testimony won't just prolong the reputational blemish, but may darken it further.

And there are issues beyond a consumer context: in another study reported in the article, adults acted as a juror in a hypothetical assault trial. On the basis of detailed eyewitness testimony for an event that happened one week ago, participants were prepared to give 11 months jail time – but if they were told the testimony concerned an event that had happened a year ago, sentences swelled to 16 months.

It's well-established that testimony larded with greater detail is likely to make more of an impression on a jury (and to be mistakenly interpreted as a sign of memory accuracy), but what this new research shows is that memory detail is likely to count for even more when a witness says they "remember it like it was yesterday."

Further reading

—Metacognitive Inferences From Other People's Memory Performance.