Credible, confident eyewitnesses are typically very convincing to juries. This makes sense; assuming witnesses to be honest, there is a tendency to believe their accounts. After all, what honest people have seen, they have seen, and not to believe the simple, straightforward evidence of their senses would be to call them liars.
The problem is that this isn’t necessarily simple or straightforward at all. Eyewitness accounts derive not from primary perception alone, but from perception and interpretation; this means that we may see logical connections where in fact they do not exist, inadvertently contaminating eyewitness accounts and essentially turning witnesses into storytellers (e.g., Yong et al., 2021). This is more common than we might expect; in experimental research, the second most common type of eyewitness error identified, after errors concerning perpetrator appearance, was that of the imagination (Sharps et al., 2009).
There are many psychological sources of such errors (e.g., Sharps, 2022, 2024), but one important source that is often overlooked is the tendency of human beings to tell stories based less on what they see than on what they think they see; and frequently, the more interesting the narrative product of these processes, the more we may believe in them.
We can see this clearly in “eyewitness” reports of the past. In the sixteenth century, supposedly based on the eyewitness account of monk and explorer Fr. Marcos de Niza, who apparently never actually said a single word about this, the deserts of the American Southwest were allegedly inhabited by a gigantic creature with a single tooth so long that the animal had to lie down to eat. No one knows the actual source of the original account. However, we do have a likely idea of the account’s provenance. A Spanish expedition into the same regions discovered a single mammoth tusk. Now, a mammoth tusk is certainly a sufficiently interesting object to attract human attention, and therefore to attract human storytelling proclivities. Nobody knew what a mammoth was at the time; but in the absence of any actual local elephantine forms for comparison, a tusk would clearly be very reminiscent of some kind of very big tooth. Since the storytelling explorers only had one tooth, they had a choice between the rather prosaic alternative of some kind of very large animal who’d lost a single tooth, or, more interestingly, some kind of animal who only had one huge tooth and therefore had to eat around it. Not surprisingly, the explorers decided they were witnesses to the more interesting alternative; not to the actual animal, but to the clear dental evidence of its presence (e.g., Sharps, 2024).
The Old World as well as the New also had its share of odd eyewitness accounts. Pliny the Elder (Rackham tr., 1940) reports, allegedly, eyewitness accounts of the mongoose, a small mammal that lives, among other places, in Egypt. There are also snakes in Egypt, some of which mongooses attack and prey on, and crocodiles, with which mongooses have nothing to do at all. Mongooses, like many small furry creatures, tend to roll in dirt to dislodge parasites from their fur. All these mongoose facts have been witnessed; but at this point, ancient eyewitnesses appear to have moved readily into the role of storytellers. This can be seen in Pliny the Elder’s accounts of mongooses rolling in dirt to construct earthen shields on their backs to defend themselves from the bites of the serpents, and of the valiant tendency of the little mammals to dive down the throats of sleeping crocodiles and gnaw their way out through the reptiles’ abdomens, dispatching the monsters in a heroic and spectacularly sanguineous fashion.
None of these things ever happened at all, of course; but eyewitnesses certainly did occasionally see a dirty mongoose fighting a snake. Somebody may also have seen a mongoose near a crocodile at some point as well, and since we really like the narrative idea of cute little underdog mammals heroically defeating crocodiles (which in the ancient world were a real menace to humans in Egypt, as they continue to be in some other parts of Africa today), we of modernity have inherited epic imaginative tales of the exploits of the mongoose, tales masquerading as serious ancient science in the authoritative Pliny, who believed the “eyewitness” accounts.
This sort of process was by no means only important in the ancient world, either. Pliny also recycles Herodotus’ story of the trochilus, a bird which lives symbiotically with the crocodile and actually enters the reptiles’ mouths to clean their teeth. The problem is that no such bird actually exists, crocodiles don’t actually need their teeth cleaned, and there is no hard evidence of this phenomenon whatsoever; yet you still encounter serious references to this extraordinary, if imaginary, symbiosis in modern works and accounts.
The trochilus is often thought to have been the Egyptian plover, although there are half a dozen other candidate birds including, in some sources, hummingbirds, which would be quite a trick since there are no hummingbirds anywhere near Africa. But if you see African crocodiles lying on mudbanks, you will note that they tend to draw an awful lot of flies. Egyptian plovers are very fond of flies, and of the various mollusks and worms inhabiting the mud around the crocodiles. Crocodiles generally tolerate the plovers. Sometimes the birds even hop onto the crocodiles or move near their faces; and somebody must have seen them do it. So, backed by the authority of Herodotus and Pliny, we have yet another “eyewitness” account, not of reality but of what somebody thought they saw, something that made a really good story, a story which has resonated through the ages to show up in modern accounts today.
Humans are storytellers as well as witnesses, and sometimes the storyteller-witnesses themselves honestly do not make the distinction. This is an important psychological reality in all walks of life; but the same dynamics must be recognized for their potential importance in eyewitness testimony in criminal investigations and in court.
