Comparison of categorical color perception in two Estrildid finches
Authors/Creators
- 1. University of Exeter
- 2. Duke University
- 3. Indian Institute of Science*
Description
Sensory systems are predicted to be adapted to the perception of important stimuli, such as signals used in communication. Prior work has shown that female zebra finches perceive the carotenoid-based orange-red coloration of male beaks—a mate choice signal—categorically. Specifically, females exhibited an increased ability to discriminate between colors from opposite sides of a perceptual category boundary than equally-different colors from the same side of the boundary. The Bengalese finch, an Estrildid finch related to the zebra finch, is black, brown and white, lacking carotenoid coloration. To explore the relationship between categorical color perception and signal use, we tested Bengalese finches using the same orange-red continuum as in zebra finches, and also tested how both species discriminated among colors differing systematically in hue and brightness. Unlike in zebra finches, we found no evidence of categorical perception of an orange-red continuum in Bengalese finches. Instead, we found that the combination of chromatic distance (hue difference) and Michelson contrast (difference in brightness) strongly correlated with color discrimination ability on all tested color pairs in Bengalese finches. The pattern was different in zebra finches: this strong correlation held only when discriminating between colors from different categories, but not when discriminating between colors from within the same category. These experiments suggest that categorical perception is not a universal feature of avian, or even Estrildid finch, vision. Our findings also provide further insights into the mechanism underlying categorical perception and are consistent with the hypothesis that categorical perception is adapted for signal perception.
Notes
"Analysis R Script.R"- This file contains all the code necessary to build the training models and
do the analysis associated with them (i.e. compare them to observed results, generate figures).
It also has the script for the AIC comparisons between models that use a category vs. contrast.
"Bengalese Finch Data," "Zebra Finch Beak Data," and "Zebra Finch Luminance Training Data" support the above R script.
They are summary datasets (i.e. population mean pass frequencies for each color comparison). For example, "Bengalese Finch Data.csv" shows
mean pass frequency across our population of Bengalese finches for each color combination.
"data" are data regarding zebra finch pass frequency on the Beak Set, originally published in [removed for double blind review]. "Zebra Finch Luminance Training Data" show zebra finch pass frequencies for the Extended Color set.
"Zebra_finch_raw_beak_set," "Zebra_finch_raw_extended_set," and "Bengalese_finch_raw_beak_and_extended_sets" contain
individual mean pass frequency for each color comparison. These data file can be used to create
things like Figures 2 and 3 (labeling and discrimination)
Column descriptions for all data files include:
bird.ID : "raw" datasets only. Individual bird ID.
cat : Color comparison
col1 : Color 1 (the redder color) in the color comparison
col2 : Color 2 (the oranger color) in the color comparison
contrast : Michelson contrast between Colors 1 and 2
chrom.dist : Chromatic Distance (Delta S) Between Colors 1 and 2
pass.freq : Proportion of comparison tasks that birds pass (population mean)
sd : Standard deviation of pass frequency
n : # of birds that completed comparisons
se : Standard error of pass frequency
training : "Bengalese Finch Data.csv": Indicates whether a given comparison is used in the training model (binary, 0=not included, 1=included)
Funding provided by: Duke University Office of the Provost*
Crossref Funder Registry ID:
Award Number:
Funding provided by: Duke University Office of the Provost
Crossref Funder Registry ID:
Files
Bengalese_Finch_Data.csv
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