Table 2.

Correlations between the psychophysical thresholds and SS and SF indexes.

Thresholds	ASD	TD	ASD	TD
	Methods of indexes calculation
	Subtraction		Residuals
High contrast	SS index
Small	–0.59**	–0.39*	0.02	0.03
Large	0.07	0.59**	0.66**	0.88**
Low contrast	SF index
Small	–0.56**	–0.72**	0.01	–0.07
Large	0.26	0.46**	0.76**	0.99**

The indexes were calculated either as the subtraction between thresholds for large and small stimuli (Subtraction) or as the residuals for the large stimuli after partialling out its correlation with small stimuli' thresholds with the regression analysis (Residuals). Asterisks denote the significance of correlation coefficient

^*p < 0.01,

^**p < 0.001.