Comparison of contrast sensitivity in macaque monkeys and humans.
Level 5 - mechanism / opinion, no new human data
Comparative laboratory psychophysical study incorporating nonhuman primate research and small human cohorts (CEBM Level 5).
PubMed 31199217 · doi:10.1017/S0952523819000051
What was done
Ten normal humans and eight normal nonhuman primates (Macaca fascicularis) were evaluated to compare contrast sensitivity functions, alongside comparisons to historical published data from Macaca mulatta and Macaca nemestrina. Contrast threshold was defined by a descending method of limits with two consecutive misses for nonhuman primates, whereas humans were tested using a descending method of limits combined with a spatial two-alternative forced choice technique. Contrast sensitivity functions were fitted with a double exponential function to evaluate peak contrast sensitivity, peak spatial frequency, visual acuity, and area under the curve.
What was found
Mean values for humans versus Macaca fascicularis were: peak contrast sensitivity of 268.9 versus 99.2 (P = 0.001); area under the curve of 2345.4 versus 980.9 (P = 0.010); peak spatial frequency of 3.40 cpd versus 3.93 cpd (P = 0.150); and extrapolated visual acuity of 27.3 cpd versus 26.1 cpd (P = 0.763). Contrast sensitivities across M. fascicularis, M. mulatta, and M. nemestrina were qualitatively and quantitatively similar to each other, but nonhuman primates had lower overall contrast sensitivity functions than humans.
Why it matters
This study provides comparative baseline parameters across primate species, demonstrating that while spatial frequency tuning and visual acuity are similar between humans and macaques, macaques have substantially lower contrast sensitivity. Researchers must account for these baseline differences when modeling human visual diseases such as glaucoma and amblyopia in nonhuman primates.
Limits
The study sample was small (10 humans and 8 M. fascicularis), and data for other macaque species came from historical publications rather than concurrent testing under identical conditions. Testing methods differed between species, as humans were evaluated using a two-alternative forced choice paradigm not used for the monkeys.
Cited by
- supports Humans do not have superior visual or auditory sensory acuity compared to monkeys.