On Trials in Which the US Occurs, a Light Precedes

question 25

Multiple Choice

On trials in which the US occurs, a light precedes a tone. On no-US trials, the tone alone is present. Later, the light is changed into a conditioned inhibitor for the US. When light is presented prior to the tone, animals still respond as if the US were forthcoming. The likely conclusion is that

• A) the light must be an occasion setter.
• B) the light could be an occasion setter, or the light and tone could be forming a configural cue.
• C) the observations must be faulty, since a stimulus cannot simultaneously facilitate and suppress responding based on the same US.
• D) the light has residual excitation.