Pop-out in visual search of moving targets in the archer fish

Mor Ben-Tov,Ronen Segev,Opher Donchin,Ohad Ben-Shahar

doi:10.1038/ncomms7476

Mor Ben-Tov, Ronen Segev + Show 2 more

Open Access

https://doi.org/10.1038/ncomms7476

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Abstract

Pop-out in visual search reflects the capacity of observers to rapidly detect visual targets independent of the number of distracting objects in the background. Although it may be beneficial to most animals, pop-out behaviour has been observed only in mammals, where neural correlates are found in primary visual cortex as contextually modulated neurons that encode aspects of saliency. Here we show that archer fish can also utilize this important search mechanism by exhibiting pop-out of moving targets. We explore neural correlates of this behaviour and report the presence of contextually modulated neurons in the optic tectum that may constitute the neural substrate for a saliency map. Furthermore, we find that both behaving fish and neural responses exhibit additive responses to multiple visual features. These findings suggest that similar neural computations underlie pop-out behaviour in mammals and fish, and that pop-out may be a universal search mechanism across all vertebrates.

Highlights

Pop-out in visual search reflects the capacity of observers to rapidly detect visual targets independent of the number of distracting objects in the background
We explored whether archer fish exhibit serial search, where reaction time depends linearly on the number of distractors
We found that the width of the bar is a salient feature for the archer fish, as the target selection rates in the different distractor conditions were significantly higher than chance

Summary

Introduction

Pop-out in visual search reflects the capacity of observers to rapidly detect visual targets independent of the number of distracting objects in the background. Differences between the target and distractors that make them distinct can result in a very efficient search that yields detection times that are independent of the number of distracting objects[4,5,6], as if the entire visual field was being processed concurrently. In these cases the target is said to ‘‘pop out’’. It is not about how often or how quickly a target is chosen, but rather how the reaction time is affected by distractors

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