The role of recall and working memory in the lives of animals
What do animals remember?
In human beings, a good memory is often seen as a sign of intelligence. When it comes to animals, a similar argument could be made.
One of the most common methods for testing animal memory is something called a radial arm maze. An animal is placed at the center of a box with a number of passages leading away. There is food at the end of one passage, but the animal does not know which one.
After checking a passage, and finding no food, the animal returns to the center. If they do not check that passage again, they must remember it has no food. This memory might last for days or weeks; this can be tested by removing the animal, then returning it to the maze later.
Remembering places
Outside of laboratory experiments, field observations can also be used to measure animal memory. Many species have excellent memories when it comes to remembering the locations of water or food.
Scatter-hoarder species, such as western scrub jays, bury caches of food underground. Studies have shown that these birds are able to recall the location of more than a hundred caches. Most humans would struggle to replicate this, as we never evolved this particular cognitive ability.
Some elephants remember the location of water for upwards of fifty years. In times of drought, the oldest members of the herd can show youngsters to a site that has not been visited for decades. When those youngsters grow up, they remember this site, and show it to the next generation.
Remembering faces
Dolphins possess an impressive capacity for remembering other dolphins. This could help them to assess social threats – did this dolphin behave like a friend or foe when the two of them met in the past?
An important experiment, in 2013, showed that dolphins still recognized the voices of other dolphins which they had not met for twenty years. This is not just a sign of long-term memory, but also of the importance of social bonds.
Similar results have been observed in elephants. In 2000, two elephants named Shirley and Jenny were reunited after more than twenty years apart. They showed signs of intimacy and recognition. Clearly, they had not forgotten each other.
Simpler brains
Dolphins and elephants have large, complex brains, so their excellent memories might come as no surprise. But animals with relatively simple brains are also able to store information in the form of long-term memories.
Insects, such as bees, have been studied extensively in an effort to understand their memory capabilities. Honeybees are able to learn the location of a food source, and in certain cases, remember that location for life.
Slugs appear to store information for approximately one month. After tasting a bitter-tasting liquid, they will avoid that liquid for the duration of the month, then forget this information, and taste the liquid again.
Goldfish are often cited as an animal with 10-second memory, but this is a myth. In reality, they often remember things for months, or in some cases, several years.
Working memory
There are plenty of examples of animals with long-term memories. But there is a lot less evidence of animals with working memories.
Working memory is the ability to remember things just for a moment, holding pieces of information in a mental workspace while we solve a problem in our heads. From an evolutionary perspective, it helps with mental problem solving.
The relative lack of scientific evidence does not mean that animals are not capable of this kind of memory. Something resembling working memory has been observed in primates, birds, and a few other groups.
But it is harder to study than long-term memory, and often relies on functional MRI scans. It will take a few more years of careful research before the topic is better understood.
Mental time travel
An important question, in animal intelligence, is whether non-human species are capable of mental time travel: thinking back to a former moment, and imagining that moment in your mind.
For a long time, this was thought to be an exclusively human trait. But in the last few years, psychologists have found signs of mental time travel in animals. When a human mentally time travels, their brain lights up in a certain way, and the same patterns have now been recorded in the brains of rodents.
Mental time travel helps us to learn from past events, and to wonder whether we might have acted differently. The same evolutionary pressures which encouraged this cognitive ability in humans seem to have encouraged it in other species too.
