Size and Loudness Constancy

The image on the retina of objects of constant size will expand and contract as the object moves closer and farther away.

Size constancy allows us to perceive objects as they are, independent of their distance from us.

**Figure 4:** The head closest to the perceiver is the same size as the farthest head.
$\scalebox{0.75}{\includegraphics{eps/head.eps}}$

A direct analog in the auditory domain is that sound intensity decreases with distance (inverse square law).

Loudness constancy allows us to percceive an increase in distance from a source if there is a decrease in amplitude.

``Music 175: Cognitive Psychology and Music'' by Tamara Smyth, Department of Music, University of California, San Diego (UCSD).