That a male European robin will attack a tuft of red feathers as readily as he will another male robin indicates that
A) an attack will be produced by almost anything.
B) intruding males and females will be attacked equally often.
C) stimulation of attack behavior requires a complex combination of stimuli.
D) the red feathers serve as a sign stimulus for attack behavior.

Question

Quizplus · Accepted Answer

The male European robin's aggressive response to a tuft of red feathers suggests that the red color acts as a specific trigger or sign stimulus for initiating attack behavior, rather than requiring a complex set of stimuli or indiscriminately attacking anything or any intruder.

That a Male European Robin Will Attack a Tuft of Red