Meeting Abstract
Female Trinidadian guppies (Poecilia reticulata) are known to assess male sexual signals on the basis of pattern elements that vary in color, size, and contrast. While color vision in guppies has long been a subject of intense investigation, much less is known about their spatial resolution and contrast threshold. Here we present the results of optomotor experiments that exposed guppies to a large rotating visual field. Stimuli were comprised of alternating dark and light vertical bars that varied in spatial frequency (i.e. stripe width) as well as contrast. Optomotor performance was scored across five different spatial frequencies, each presented at seven different Michelson contrast values. Our results are presented as a contrast sensitivity function (CSF), which represents guppy contrast sensitivity as a function of spatial frequency. The CSF allows for an estimation of visual acuity and identifies the spatial frequencies to which a given visual system is maximally sensitive. Because spatial resolution and contrast sensitivity limit the details which can be resolved within a given scene, the CSF contributes to our understanding of the pattern elements which may be most salient within a visual signal. As such, our results are interpreted within the context of sexual signaling and pattern evolution in Poecilia reticulata.
