Apsychological scientist asks study participants to indicate whether the green line at the front corner of the wall pictured here is longer than, shorter than, or equal in length to the green line at the back corner of the wall. participants regularly say that the front line is shorter than the back line (even though the two are perfectly equal in length). the participants’ brains are using to guide perception.

contextual cues about depth

Explanation:

Based on the information provided within the question it seems that the participants' brains are using contextual cues about depth to guide the perception. This can be said because the brain is subconsciously measuring both lines in relationship towards each other as well as various objects around the lines at different depths, which would lead to inaccurate measurements as opposed to comparing the lines together at the same depth perception.

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