Experiments suggest that animals, just like humans, tend
to prefer exaggerated, supernormal stimuli, and that a
preference can rapidly propel itself to extreme levels (peak
shift effect). In one experiment, through food rewards rats
were conditioned to prefer squares to other geometric forms.
In the next step, a non-square rectangle was introduced and
associated with an even larger reward than the square. As
expected, the rats learned to reliably prefer the rectangle.
Less predictable was the third part of the experiment. The
rats were offered the opportunity to choose between the
rectangle they already knew and associated with large
rewards and another rectangle, the proportions of which
were even more different from those of a square.
Interestingly, rats picked this novel variant, without
undergoing any reward-based conditioning in favor of it. A
possible explanation is thus that they chose the larger
difference from the original square (i.e., the exaggeration of
non-squareness).
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In an experiment, after first establishing an (A) to
squares, and then to non-square rectangles, rats were seen
to pursue (B) rectangularity even without any
additional reward.
(A) (B) (A) (B)
① inclination …… severe ② opposition …… familiar
③ inclination …… vague ④ opposition …… unexpected
⑤ attachment …… subtle