Table 1.

Subject characteristics

	Low compulsive group	High compulsive group
Age*	21.40 ± 2.52	20.75 ± 2.34	t(38) = .85, p = .403
Gender (f/m)*	13/7	14/6	χ(1) = .114, p = .736
Handedness (r/l)	16/4	16/4	χ(1) = .0, p = 1.00
IQ (WASI total)	115.6 ± 10.9	115.4 ± 9.8	t(38) = .06, p = .952
PI-WSUR total*	5.3 ± 4.0	50.2 ± 18.3	t(38) = 10.74, p < .001
MFQ*	19.1 ± 8.9	19.4 ± 11.7	t(38) = .07, p = .942
RCMAS total*	20.7 ± 10.1	18.7 ± 10.7	t(38) = −.61, p = .545
BDI-II total	6.1 ± 4.2	8.7 ± 7.1	t(38) = 1.41, p = .166
STAI (trait)	38.3 ± 6.5	41.4 ± 11.3	t(38) = 1.05, p = .302
STAI (state)	33.5 ± 6.1	34.0 ± 9.4	t(38) = .20, p = .843
BIS	58.30 ± 6.87	59.04 ± 9.74	t(38) = −.28, p = .782
Intolerance of uncertainty	48.75 ± 15.14	58.80 ± 15.87	t(38) = −2.05, p = .047
FMPS total	98.02 ± 16.21	103.02 ± 17.35	t(38) = −0.94, p = .353

Subjects were recruited from a population-based database so that groups differed maximally on the compulsivity spectrum (PI-WSUR)²¹, but were matched for age, gender, depression (MFQ)²² and anxiety (RCMAS)²⁴. The groups did not differ in depression (BDI-II)²⁷, anxiety (STAI)²⁶, impulsivity (BIS)²⁸, handedness³⁰ or intellectual abilities (WASI)²⁹, as assessed on the day of the experiment. Groups differed in their intolerance of uncertainty³³, but not in perfectionism (FMPS)⁴⁶. (mean ± SD); *data used for recruiting participants