73 — Pigeon Perception of Letters of the Alphabet

In 1982, pigeons were placed inside a box with a TV, and an ATARI “home computer” (I love that this was the equipment used) generated three black (5×7-dot) letters on a white background. The pigeons were trained to peck at a “target” letter during each trial; the target remained the same for several sessions in order to best train the birds.

The birds were rewarded for pecking the same letter, and went unrewarded for pecking the wrong letters. In this way, the researchers were able to determine which letters were most often confused for other ones by the pigeon visual perception system.

The researchers then used these similarities to reduce the results to a 2D grid; letters that were commonly grouped together were the ones birds most commonly confused (for example, I and T). Letters that were far apart from each other were most commonly differentiated successfully (for example, E and U).

From this dataset, Blough et al were able to learn about the specific features captured by the bird attention, and which were ignored.

I found it interesting that A and R were more commonly confused than R and P (P was more commonly confused with B). Similarly, E and B were infrequently confused; this makes me think that the pigeon brain was more selective to topology of the letters (the paper mentions “closed” sides as a common differentiator for letters) rather than the exact shape; A and R are similar topologically even where their shapes vary.