**3. Results**

## *3.1. Behavioral Data*

The mean CFT-20 R score ( ± standard deviation) was 77.1 ± 7.8, which is equivalent to a transformed mean intelligence quotient (IQ) of 98.8 ( ± 11.4). Table 1 provides means and standard deviations of RT in the three conditions of the CPT. A one-way analysis of variance (ANOVA) with CPT conditions as three levels of a repeated-measures factor revealed statistically significant differences in RT, *F*(2, 218) = 1978.510, *p* < 0.001, *ηp* 2 = 0.948. As indicated by Bonferroni-adjusted post-hoc *t* tests, RT increased significantly from the CPT0 to the CPT1 condition, *t*(109) = 46.700, *p* < 0.001, *d* = 4.453, as well as from the CPT1 to the CPT2 condition, *t*(109) = 17.869, *p* < 0.001, *d* = 1.704.

Also given in Table 1 are descriptive statistics of errors of omission in the three CPT conditions and errors of commission in the CPT1 and CPT2 condition. (Due to the lack of distractors in the CPT0 condition, participants could not make errors of commission in this condition.) As indicated by a one-way ANOVA on omissions with the three CPT conditions as levels of a repeated-measures factor, omissions differed significantly between the three task conditions, *F*(2, 218) = 11.550, *p* < 0.001, *ηp* 2 = 0.096. There were significantly more errors of omission in the CPT0 than in the CPT1 condition, *t*(109) = 4.762, *p* < 0.001, *d* = 0.454, while omissions in the CPT1 and the CPT2 did not differ significantly after Bonferroni adjustment, *t*(109) = 2.152, *p* = 0.034, *d* = 0.205. Errors of commission, however, were made more frequently in the CPT2 than in the CPT1 condition, *t*(109) = 11.317, *p* < 0.001, *d* = 1.079.

Pearson correlations between RT in the three conditions are reported in Table 2. All three correlation coefficients yielded statistical significance. Unexpectedly, however, the correlations between RTs in the three CPT conditions and CFT-20 R scores were not significant and even positive in the most demanding task condition.

Similarly, CFT-20 R scores did not significantly correlate with errors of omission in the three task conditions (CPT0: *r* = −0.006, *p* = 0.949; CPT1: *r* = −0.132, *p* = 0.171; CPT2: *r* = −0.101, *p* = 0.293) nor with errors of commission in the CPT1, *r* = −0.054, *p* = 0.578, and in the CPT2 condition, *r* = −0.116, *p* = 0.229.


**Table 1.** Descriptive statistics of reaction times, errors of commission, and errors of omission in the three conditions of the continuous performance test (CPT) in 110 participants. No errors of commission were possible in the CPT0 condition.

 M = Means, SD = standard deviation, Min = minimum, Max = maximum.


Reaction times CPT0 0.437 \*\*\* 0.366 \*\*\* 0.213 \* 0.133 0.041 –0.244 \*\* –0.272 \*\* –0.249 \*\*

CPT1 0.600 \*\*\* 0.077 0.293 \*\* 0.215 \* –0.226 \*\* –0.339 \*\*\* –0.241 \*\* CPT2 0.209 \* 0.124 0.086 –0.144 –0.218 \* –0.305 \*\* P3 latencies CPT0 0.029 –0.046 –0.262 \*\* –0.170 \* –0.273 \*\*

CPT1 0.500 \*\*\* –0.010 –0.154 –0.160 \* CPT2 0.111 –0.103 –0.016


\* *p* < 0.05; \*\* *p* < 0.01; \*\*\* *p <* 0.001 (one-tailed).

P3 amplitudes CPT0 0.404 \*\*\* 0.339 \*\*\*

CPT1 0.686 \*\*\*
