The feature-positive effect in adult humans: within-group design.

The feature-positive effect has been demonstrated in several species and has been shown to be robust phenomenon in adult humans when between-group designs are used. The present series of experiments replicated earlier work using between-group designs, found the feature-positive effect using within-group designs, and isolated a factor responsible for an earlier failure to find the phenomenon using a within-group design. The results support the argument for a biological, evolutionary influence in the genesis of the feature-positive effect.