Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Spectral shape index, defined as the ratio of the first harmonic amplitude to the mean of the second and third harmonic amplitudes, plotted as a function of RMS cone contrast for one participant (top) and averaged over all participants (bottom). In the graph for a single participant (top), error bars were calculated from the Tcirc2 statistic of Victor and Mast (1991). For the grand average (bottom) the error bars represent ±1 SEM.
