Ebbinghouse illusion task

[celefthe]

Task to test whether mice are susceptible to the Ebbinghouse illusion of relative size perception (see https://en.wikipedia.org/wiki/Ebbinghaus_illusion).

The task should be implemented in 3 stages:

1. Two different sized circles, bigger is rewarded.
2. Introduce context (i.e. surrounding circles), centre circles are still distinctly larger
3. Centre circles are the same size, context varies to generate a psychometric curve.

Context circles should be no further than 30 degrees apart.

[celefthe]

See https://www.nature.com/articles/s10038-020-00827-4#Sec2 and https://link.springer.com/article/10.3758/bf03194895 for example implementations (in humans)