Guppies Raised on Screens Develop Brain Abnormalities

A new study from the Department of Zoology at Stockholm University, Sweden, has revealed surprising facts through trials on guppies (Poecilia reticulata). Young fish that only interacted via a video screen experienced brain development similar to fish living in total isolation. The study, led by Olivia Carmstedt for her master’s thesis, deliberately chose guppies because of their high brain development flexibility. “Fish are a very good model for studying brain plasticity because their brains continue to develop throughout their lives,” explained Professor Niclas Kolm, the study’s senior author. In an experiment lasting 20 days, researchers divided young guppies into three different environmental conditions. The first group was placed next to an aquarium containing live fish they could see and interact with. The second group was only presented with video recordings of other guppies on a monitor screen. Meanwhile, the third group was raised in near-total isolation without any companions at all. All environmental variables were kept identical, from food and water quality to lighting. The sole difference was the type of social stimulation they received. The group watching videos actually received the same visual information as the first group, but they missed the aspect of two-way feedback from real interaction. When the research team measured the brain volume of these fish, the results were startling. The group that grew up alongside live fish had brains almost 6% larger than the group that only watched screens. Furthermore, this direct interaction group also developed a significantly larger olfactory bulb. What was most surprising for the researchers was the condition of the screen-watching group. Instead of falling somewhere between the direct interaction and isolated groups, the brain structure of the screen-watching guppies was almost identical to fish raised in total isolation. “The interaction itself, the fact that another individual responds to you in real-time, appears to be very important for normal brain development,” Carmstedt revealed. Simply watching visual footage proved not to have the same impact as real interaction. However, this difference in brain size did not affect their basic non-social cognitive abilities. When tested using an object permanence test, the ability to track a target that has disappeared from view, akin to a baby understanding a hidden toy, all three groups performed equally well. This indicates that social experience specifically shapes certain brain areas, not overall intelligence. Although humans are not guppies and these results cannot be directly matched to the impact of tablets on toddlers, the findings provide an important analogy in the screen time debate. The study suggests the quality of interaction is far more important than the quantity of visual information. Two-way video calls with family members, where there is real-time reciprocal response, are thought to provide much better stimulation for a developing brain than simply watching passive, one-way content. The research has been officially published in the journal Biology Letters.