This post was written by ScIU Social Media Intern Junhui Wu, an undergraduate student in The Media School at Indiana University.

Have you ever dreamed about having a good relationship with your pet from day one? I believe that all pet owners have good hearts and the intention of sharing their lives with these cute creatures. Unlike dogs, who are often thought of as the symbolic figure of human beings’ most loyal friends, cats are considered more conservative in terms of revealing their feelings or emotions towards their owners. There is one pet’s feelings, however, that people might find more challenging to interpret — goldfish. 

Do goldfish have emotions and perceive the feelings of their owners, like other common household pets? Do goldfish remember their past experiences with their owners? In today’s blog post, I will introduce you to some scientific studies on learning and memory in goldfish and discuss what has been discovered so far. 

According to the American Museum of Natural History, fish use spatial cognition, and there are areas within a goldfish’s brain that are analogous to the hippocampus in humans, a region that has a major role in learning and memory. In a series of studies, a Young Naturalist Award winner used goldfish as an animal model to help us understand learning and memory in the human brain. After training goldfish to find a food reward using a training maze, she tested their ability to find the reward in a testing maze. The testing maze, which contained several obstacles that could be rotated relative to the training maze, was used to assess whether goldfish are capable of adjusting their strategy for finding the food reward. She discovered that goldfish successfully found the food and bypassed the obstacles, both when the testing maze was in the identical orientation as the training maze and when the testing maze was rotated 180 degrees relative to the training maze. These results suggest that goldfish can recall spatial tasks and can adjust these tasks based on changes in their surroundings. 

But, are goldfish capable of performing similar tasks after receiving long-term training? Dr. Morton Bitterman, a former professor at the University of Hawaii, conducted an experiment on the role of Conditioned Stimulus-Unconditioned Stimulus (CS-US) intervals on learning in goldfish. CS-US is a form of classical conditioning, in which two stimuli are paired together repeatedly during a training period and a response, which is at first elicited by the second stimulus (also known as the unconditioned stimulus, or US), is eventually elicited by the first stimulus (also known as the conditioned stimulus, or CS) alone during the testing period. In this study, Dr. Bitterman used aversive conditioning, in which he paired a neutral conditioned stimulus (light) with a negative unconditioned stimulus (shock) and compared the activity and spatial distribution of goldfish trained at different CS-US intervals. He found that during the testing period, goldfish showed a decrease in aversive responses to light as the interval between the presentation of the CS and US increased, supporting Pavlov’s original interpretation of classical conditioning. Dean Pomerleau, a research scientist and fish trainer, also showed that goldfish can perform a number of tricks after receiving an extended period of training with a food reward. 

Based on these experiments and others, it appears that goldfish are smarter than some people may think! These studies suggest that goldfish respond to classical conditioning and use spatial cognition to seek out resources in their environment. Using goldfish to learn about memory and spatial cognition can help enhance our understanding of memory loss. According to a Dailymail article, a recent study conducted by Dr. Toshiyuki Sawaguchi, a professor of neurobiology at Japan’s Hokkaido University, and his colleagues showed that a third of the women tested under the age of 30 exhibit memory deficits, including failing to remember their own phone number and recall the birthdays of three of their close relatives. This “memory fading” is believed to be a consequence of modern life conveniences, such as computer gadgets and organizers, which many of us rely on to remember things for us. This idea closely matches a concept called goldfish memory syndrome, in which a person easily loses their thoughts and forgets things. Nevertheless, this expression still lives on, even though the studies presented in this post suggest that it’s a myth. While the concept of memory-deficient goldfish still pervades our society, we are beginning to understand that, in fact, a goldfish’s memory lasts far longer than just seven seconds. 

References:
Bitterman, M. E. (1964). Classical conditioning in the goldfish as a function of the CS-UCS interval. Journal of Comparative and Physiological Psychology, 58(3), 359–366.
Salas, C. et al. (2006). Neuropsychology of learning and memory in teleost fish. Zebrafish, 3(2), 157–171.

Edited by Kat Munley and Ben Greulich