Animal trainers' expectations may have led them to interpret some chimpanzees' signs as indicative of greater linguistic ability than is warranted. This best illustrates the shortcoming of

a perceptual set

Explanation:

A perceptual set -

It refers to the condition, where the mind perceive only certain specific thing, ignoring the rest objects, is referred to as a perceptual set.

It is not necessary than the mind of mammals tends to remember all the things he see around him, as he only remember only very limited objects.

Hence, from the given scenario of the question,

Chimpanzees' too remember only certain things.

Therefore, the correct term is a perceptual set.