Darla is a student studying the relationship between physical stimuli and peoples' perceptions of those stimuli. in which academic area is darla earning her degree

Psychophysics

Explanation:

Psychophysics is a science that focuses on studying the relationship that exist between stimuli and the percetions and sensation that are brought out by those stimuli.

The example would be judging the mangitude colour difference against the standard colour in order to see how sensitive an individual is to the effect of each colour.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.