Creatures of habit: the persistent problem of instincts

From the behaviour of the smallest creatures to the dynamics of a crowd of humans, it seems that behaviour is governed by a finite set of rules. So what is it that drives humans and animals alike? Do we really make our own decisions or is it a matter of animal instinct?

Dr Ashley Ward, from the School of Biological Sciences studies the social behaviour of animals, using fish to model complex animal behaviour and its associated costs and benefits.

“We tend to assume that, like humans, fish are visually biased. In actual fact many fish predominantly use olfactory cues to form shoals, find food and avoid predators.” Ward is keen to understand the human influence on fish, and Ward has discovered some eerie facts about animal decision-making, which have some startling ramifications for human behaviour.

“A trust in consensus decision-making underlies many of our democratic political and judicial institutions. What can we learn about this decision-making process by studying animals and what can we learn about ourselves?” asks Ward.

If they find themselves in a novel situation, a lone fish, or those in a small group, are fairly happy to put their faith in a leader, even in the face of danger. “It’s easy to lead one fish astray. However, large groups won’t be fooled by one rogue leader, but are more easily swayed by a pair of fish.”

Ward has discovered that it’s a quorum response that governs this behaviour. The logic behind this response is that an individual could conceivable make an error, but it’s much less likely that two individuals would make the same mistake. “This is an important system, my studies have shown that as group size increases so too does the accuracy of decision-making,” reveals Ward.

Strangely it seems that the time it takes to make a decision is constant despite increasing group numbers, a prediction made by mathematical models. “Often mathematical models suggest outcomes I wouldn’t expect and these kinds of predictions allow me to look at problems from a whole new light.”

Delving deeper into the dynamics of decision-making, Ward has considered whether all leaders are created equal. “What qualities make a leader attractive? Large or small, fat or thin, dark or light?” As it turns out an individual fish can have a slight bias in each case, usually towards the type of leader that has attributes associated with foraging success, like size. “When we increase the numbers of follower fish their bias for a particular trait becomes magnified.”

Currently Ward is conducting a world first study into animal group leadership. This time Ward trains fish to expect food in a certain location, and then introduces them to a group of fish accustomed to finding food elsewhere. “Will these fish trust their own knowledge, or will the group override their knowledge? I expect it will, their first imperative is to stay with a group, their second is to find food,” posits Ward.