Illustration of whether fishes are right- or left-brained

Fish are neither right- nor left-brained

Monday 31 Aug 20


Tommy Norin
DTU Aqua

The asymmetric expression of cognitive functions – knows as behavioural lateralization – is reported to enhance key fitness-relevant traits such as group coordination, multitasking, and escape from predators. Previous studies have reported negative effects on lateralization in fish due to environmental stressors such as ocean acidification, hypoxia, and pollutants, which is worrisome. However, such studies generally use a detour test that is prone to experimenter bias, and they focus on population level measures without validating whether lateralization is consistent within individuals across time.


Together with international colleagues, Dr Tommy Norin – a researcher at the Centre for Ocean Life – attempted to replicate previous findings of strong lateralization in fishes. Using a carefully designed detour test and new statistical methods, the researchers tested if individual fish from four different species were indeed consistently lateralized and preferred to turn to one side or the other when the fish found themselves at a crossroad. The researchers were unable to reproduce previous findings of strong lateralization in fishes, calling into question functional inferences drawn by many published studies.


Read the paper here.



Roche DG, Amcoff M, Morgan R, Sundin J, Andreassen AH, Finnøen M, Lawrence MJ, Henderson E, Norin T, Speers-Roesch B, Brown C, Clark TD, Bshary R, Leung B, Jutfelt F & Binning SA (2020) Behavioural lateralization in a detour test is not repeatable in fishes. Anim. Behav. 16, 55-64.
22 APRIL 2021