The 3 second memory

Now that the fish have settled in, it is time to start putting them to work. In order to understand more about how the brains of fish work, I study their behaviour. While some researchers studying animal behaviour observe animals acting naturally in the wild, I run experiments in the lab designed to determine if fish can perform specific tasks.Whether or not they can perform a specific tasks can tell me important information about how their brains work.

A really simple example would be if we asked the question: do fish see colour? To answer this, we can present the fish with two identical objects, except that one is blue and the other is red. We can train the fish to select one of the objects, either the red or blue. If they can learn to select a particular object then we know the fish are able to see two colours. Now there is a lot more to testing colour vision, but this is the general idea of how I use behavioural experiments to answer complex questions.

I mentioned that I train fish… When I say this, most people give me a blank look and then ask: ‘but don’t fish have a 3 second memory?’ So before I explain how this is done, I need to pause and just clear up a little myth about fish.

FISH DO NOT HAVE A 3 SECOND MEMORY!!!

Ok now that we have that out of the way… To train fish, I use operant conditioning. Operant conditioning means that I use a positive reward to reinforce a behaviour that the fish would naturally do. In this case, the fish will naturally bite at things that are put in their tank. When they bite at the item I want, I reward the fish with a piece of food. This form of training only works if the fish are interested in performing the task. Luckily for me, triggerfish are curious by nature and love to bite at whatever I put in their tanks. And of course they love food!

At the beginning of this video, a fish is behind a white wall with a sliding door. When I open the door, the fish swims through. There they can see another white board with four circles on it. These circles are printed pieces of paper that are laminated. I stick them to the board with velcro dots.

You can then see the fish take a bite at the darkest one. This is the correct response from the fish, and I therefore feed the fish using forceps (because they bite!). My favorite bit is how the fish then swims back through the door to wait to start the process all over again.

I love this door that I had made as it provides a clear indicator to the fish of when a trial begins, and it protects me from being bitten when I put the stimuli board in the tank. However sometimes the fish get impatient with me and start spitting water at me out of the tank. Such demanding little fishies!

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