Visual Capability & Perceptual Processing Banner
Credit: E Caves

Animals assess one another using signals in a range of contexts that are critically important for survival and reproduction, from mate choice to agonistic encounters. Two key factors that influence the receiver’s interpretation of visual stimuli are the physiology of the sensory system, as well as perceptual processes that occur after a stimulus is transduced by a sensory organ. Our research in this area uses a variety of techniques to quantify animal visual capabilities (with a particular focus on visual acuity, the ability to perceive detail), and behavioral assays to examine how animals respond to variation in signal form and information.

Visual Acuity

Acuity is an understudied yet ecologically and behaviorally important aspect of visual capability, as it dictates what details an animal can or cannot resolve in a given scene. It is also extremely variable across species, spanning at least four orders of magnitude in animals with image-forming eyes. Our research on visual acuity focuses on describing cross-species variation in acuity, exploring the ecological and morphological factors underlying that diversity, using behavioral assays to integrate measures of acuity with studies of signaling.

Current projects include:

  • Developing a database of acuity across species, in collaboration with Dr. Nick Brandley (Wooster College)
  • Describing the diversity of acuity across species and exploring the ecological and morphological factors underlying that diversity
  • Exploring how visual acuity may act as a selective force on signal form


Perceptual Processing

Sensory physiology alone does not entirely predict what an animal ultimately perceives, because a number of perceptual processes can occur after a stimulus is transduced by a sensory organ (the retina in the case of visual stimuli). Such perceptual processes can alter signal detectability, discriminability, or memorability; result in discontinuous perception of continuous variation; group or segregate stimuli to form perceptual objects; and integrate the components of multi-modal signals. Our research in this area uses behavioral assays to probe perceptual processing, in particular comparing behavioral performance with what is predicted based on sensory physiology alone.

Current projects include:

  • Proportional processing of stimulus magnitude in swordtail fish, in collaboration with Dr. Laura Kelley
    • this project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement, No 793454


Relevant Publications

T Dixit, EM Caves, CN Spottiswoode, and NPC Horrocks. Why and how to apply Weber’s Law to the coevolution of models and mimics. (Accepted). Evolution.

EM Caves and S Johnsen. 2021. The sensory impacts of climate change: bathymetric shifts and visually-mediated interactions in aquatic species. Proceedings of the Royal Society B. 288: 20210396. Covered by:, Energy & Environment News

EM Caves, PA Green, MN Zipple, D Bharath#, S Peters, S Johnsen, and S Nowicki. 2021. Comparison of categorical color perception in two Estrildid finches. The American Naturalist: 197: 190-202.

EM Caves, J Troscianko*, and LA Kelley*. 2020. A customizable, low-cost optomotor apparatus: a powerful tool for behaviourally measuring visual capability. Methods in Ecology and Evolution.

EM Caves, LE Schweikert, PA Green, C Taboada, MN Zipple, S Peters, S Nowicki, and S Johnsen. 2020. Variation in retinal carotenoids correlates with variation in perception of carotenoid coloration. Behavioral Ecology and Sociobiology. DOI:10.1007/s00265-020-02874-5

EM Caves, S Nowicki, and S Johnsen. 2019. Von Uexküll revisited: Addressing human biases in the study of animal perception. Integrative and Comparative Biology. DOI:10.1093/icb/icz073

MN Zipple*, EM Caves*, PA Green, S Peters, S Johnsen, and S Nowicki. 2019. Categorical perception in non-signalling versus signalling color ranges in a songbird. Proceedings of the Royal Society B: 286, 20190524

EM Caves*, PA Green*, MN Zipple, S Peters, S Johnsen, and S Nowicki. 2018. Categorical perception of colour signals in a songbird. Nature. 560: 365–367.

EM Caves, NC Brandley, and S Johnsen. 2018. Visual acuity and the evolution of signals. Trends in Ecology and Evolution. 33: 358-372.

EM Caves, TT Sutton, and S Johnsen. 2017. Visual acuity in fish correlates with eye size and habitat. Journal of Experimental Biology 220: 1586-1596.

EM Caves and S Johnsen. 2017. AcuityView: An R package for portraying the effects of visual acuity on scenes observed by an animal. Methods in Ecology and Evolution 9: 793-797.


Affiliated Researchers

Assistant Professor
Ecology, Evolution, and Marine Biology
Vision, behavioral ecology, animal behavior, evolution; visual perception in animals; signaling behavior, form, and perception.