Animals have memories, but do they have human-like memories? Although they can recognize, associate, and use memory to understand the world, animals seem to lack the power to recollect and think about the past in a reflective, autobiographical way.
Animals display surprising powers of memory – none more so than chimpanzees, a species very closely related to our own. Experimenters tested a chimpanzee by leading it around a one-acre compound as they concealed 18 pieces of fruit in different hiding places. Each time they set the chimp free after a few minutes, it found, on average, about 12 of the treats – a performance not significantly worse than the average human’s. When the mix of food was concealed, the chimp went straight to whichever morsel it liked best. The chimp appeared to have a pretty clear memory of both where and what had been stored.
Memory for survival
While most animals are not as intelligent as chimpanzees, all show some level of memory. Even a snail learns to avoid a particular smell if it is paired with an electric shock. Goldfish do not seem to remember anything for more than about ten seconds, but equally, this means that they can remember something for about that long, such as which way to swim to find food or to avoid a shock. Other fish, particularly large varieties, do much better, performing more like lizards. If a lizard is shown food being put behind an obstacle, it will head for the food, even if it is held back for two or three minutes. So, out of sight is not out of mind, even for reptiles.
Some animals have considerably longer memories. In one study, experimenters fed cats, dogs, and baboons in the corner of a particular room. Let loose at the door to this room for weeks or even months later; the animals would head straight over to sniff and scratch at the same corner. Birds show particularly prodigious memories. Every November, Clark’s nutcracker, a North American jay, collects pine seeds and buries them for safe-keeping in thousands of caches to keep them going through the winter and spring. Even after several months, the bird can go straight to each stash – a feat of memory that humans would struggle to match. When the researchers moved rocks and tree stumps around, the birds became confused, which showed that they used visual landmarks to remember their troves.
Absent autobiography?
It seems that animals have no trouble laying down memories that can be mobilized in response to immediate experiences and needs. A particular sight, sound, or smell will be instantly recognized and may even spark associations. Hunger pangs and other internal urges can also ring the bells of memory, awakening ideas in an animal about how to respond. The difference with humans is that we seem able to delve into our memory banks at will.
We can recall – or at least recoil struct – fairly convincing images of various life events, from what we had for breakfast to a particularly enjoyable concert or party. However, it is a consensus among animal psychologists that animal minds seem to lack this kind of reflective recollection. The difference may lie in language. Speech helps us to categorize memories and also seems to be involved in the organization of our reminiscences. When we prod our memory banks with a questioning inner voice, words like ‘breakfast ‘ and ‘birthday part strike sparks of association. Words act as a stimulus, and recollection of ourselves in another time and place unfolds with a narrative structure.
So, animals can display some impressive powers of recollection. But for whatever reason, only humans appear to live auto-biographically.
Not so bird-brained
Pigeons have brains 500 times smaller than human brains, but experiments have shown them to have unexpectedly good powers of recognition. Using seed as a reward for correct answers, pigeons were trained to pack at a button whenever they were shown 1 photograph depicting some chosen feature. The tests revealed that pigeons quickly learn to distinguish photos containing trees from photos without – they could even tell oak leaves from other kinds of leaves. Next, pigeons were tested on pictures with people and no people, single people or crowds, clothed or unclothed people, and eventually on pictures with or without a particular woman. They learned to recognize the woman from any angle and were able to distinguish her from pictures of other women dressed in similar clothes. The pigeons’ remarkable performance even held up in tests involving pictures of fish and sea creatures – not normally within the experience of the average pigeon.
An elephant remembers
The old saying that an elephant never forgets may not be as far-fetched as it sounds. Randall Moore, a Kenyan elephant expert, returned a captive elephant to the wild. Fifteen years later, the same elephant was found with an injured foot after an attack by a hippopotamus. The elephant violently resisted all attempts at help until Moore went out and called to it. The elephant seemed to recognize his voice immediately.
An onlooker reported: ‘It came up to him and laid down and allowed a vet to examine it. The elephant lifted his foot and was passive while his rescuers put in syringes and operated.
