The visual acuity of the pigeon for distant targets.
Pigeons see about three to five times less detail than humans, so make visual cues large and bold in any avian discrimination task.
01Research in Context
What this study did
Researchers tested how sharp a pigeon's eyesight is. They used black-and-white stripes on a screen. The birds had to peck the side with stripes, not gray.
Humans tried the same setup. This let the team compare pigeon and human vision under identical lab lights and distances.
What they found
Pigeons could still see the stripes when each bar was about 1–4 minutes of arc wide. Humans in the same box could see stripes down to 0.8 minutes of arc.
In plain words, pigeons resolve detail about three to five times worse than we do.
How this fits with other research
Demello et al. (1992) later ran the same forced-choice task with hens. The hens scored 4–6 cycles per degree, a similar ballpark to the pigeon results. Both studies show birds land in the same rough acuity window.
Hodos et al. (1976) asked a different question: how slow can a moving spot go before a pigeon notices it? They found thresholds near 4–6 mm/s. Taken together, the 1971 acuity data and the 1976 motion data map out two basic limits of pigeon vision.
No contradictions appear; each paper measures a separate visual dimension with shared operant methods.
Why it matters
If you use touchscreen tasks with pigeons or other birds, keep stimuli well above 4 minutes of arc. Tiny text or thin lines will drop out for them. Use bold, high-contrast cues and check that your display distance matches the lab setup in Blough (1971).
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02At a glance
03Original abstract
The acuity of six pigeons was measured in an apparatus that required the birds to make visual discriminations at a distance of 28.75 in. (73 cm) from the stimulus targets. The stimuli were black and white gratings of varying stripe width. A forced choice procedure was used, and both the Method of Constant Stimuli and a descending series technique determined the order of stimulus presentation. Thresholds, obtained by interpolating at the 25% error point on the psychometric functions, ranged from 1.16 to 4.0 min of arc. Thresholds measured in the same apparatus for two human observers were 0.79 and 0.82 min of arc. The descending series design produced lower per cent error rates at the widest stripe value, but otherwise there appeared to be no difference between psychophysical methods. Position preferences occurred in most of the birds; differential per cent error functions and differential latency functions to the two keys illustrate these. Retinal histology revealed shallow, centrally located foveae in the three pigeon breeds used.
Journal of the experimental analysis of behavior, 1971 · doi:10.1901/jeab.1971.15-57