Any simultaneous pair of partials of about the same amplitude that is less than a critical bandwidth apart produces roughness associated with the inability of the basilar membrane to separate them clearly.
In terms of psychophysics, several studies have been done involving a person’s ability to detect the differences between the weight and roughness of objects.
Patients with this somatosensory cortical loss syndrome commonly display damage to their parietal lobe and it was eventually concluded that it may be that the brain has some form of an asymmetrical organization, as performance in a normal subject shows oblique differences depending on their hand use.
However, these patients still exhibit normal or minimally reduced peripheral sensitivity to cold, heat, pain, touch and deep pressure.
Also, there were early observations stated that scanning velocity and contact force between the finger and a surface have minor or no effect on roughness magnitude judgments.