Psychopharmacology (2012) 220:293–301 Table 1 Difference scores from placebo for the tracking test and divided attention test ΔSDLP Tracking test Divided attention test 298 Treatment Zolpidem (20 mg) Alprazolam (1 mg) Zolpidem (10 mg) Diphenhydramine (50 mg, day 1) Oxycodone/paracetamol (10/650 mg) Diphenhydramine (50 mg, day 4) Alcohol (BAC=0.05%) Bromfenac (50 mg) Levocetirizine (5 mg, day 4) Zaleplon (10 mg) Zaleplon (20 mg) Levocetirizine (5 mg, day 1) Oxycodone/paracetamol (5/325 mg) Bromfenac (25 mg) Overall N 30 18 30 48 18 48 29 18 48 30 30 48 18 18 491 +10.41a +9.62a +3.35a +2.74a +1.87 +1.56a +1.03a +0.51 +0.46 −0.45 +0.43 +0.22 −0.65 −0.66 +2.09 Easy 0.694** 0.447 0.245 0.252 0.246 −0.133 0.185 0.225 0.167 0.229 0.039 0.029 0.598** 0.545* 0.412** N=431 RT reaction time, SDLP standard deviation of lateral position, N number of subjects *p<0.05, **p<0.01; significance of correlation a SDLP differed significantly from placebo SDLP, stepwise regression analyses were conducted. The DSST was excluded after a first analysis because the test did not contribute to the predictive validity. Table 3 shows the results of the regression analysis including the remain- ing test parameters. The combination of five parameters, hard tracking, tracking, and reaction time of the divided attention test, and reaction time and percentage of errors of the Sternberg memory scanning test, together had a predictive validity of 33.4%. The parameters easy tracking and percentage of ΔSDLP Sternberg memory scanning DSST Table 2 Difference scores from placebo for parameters of the Sternberg memory scanning test and DSST RT reaction time, SDLP standard deviation of lateral position, DSST digit symbol substitution test, N number of subjects, N/D test was not included in test battery *p < 0.05, **p < 0.01; signifi- cance of correlation aSDLP differed significantly from placebo Treatment Zolpidem (20 mg) Alprazolam (1 mg) Zolpidem (10 mg) Diphenhydramine (50 mg, day 1) Oxycodone/paracetamol (10/650 mg) Diphenhydramine (50 mg, day 4) Alcohol (BAC=0.05%) Bromfenac (50 mg) Levocetirizine (5 mg, day 4) Zaleplon (10 mg) Zaleplon (20 mg) Levocetirizine (5 mg, day 1) Oxycodone/paracetamol (5/325 mg) Bromfenac (25 mg) Overall N 30 18 30 48 18 48 29 18 48 30 30 48 18 18 491 Hard 0.602** 0.875** 0.387* 0.285* 0.630** 0.031 0.072 0.241 0.330* 0.201 0.292 0.459** 0.719** 0.415 0.444** N=431 +10.41a +9.62a +3.35a +2.74a +1.87 +1.56a +1.03a +0.51 +0.46 −0.45 +0.43 +0.22 −0.65 −0.66 +2.09 Tracking 0.660** 0.693** 0.250 0.255 0.496* 0.224 0.065 0.092 0.397** 0.442* 0.079 0.229 0.536* 0.539* 0.470** N=431 RT 0.713** 0.510* 0.333 0.156 0.375 0.050 0.261 −0.071 0.055 0.308 0.326 0.046 0.349 0.193 0.435** N=431 RT 0.599** 0.372 0.348 0.012 0.262 −0.166 0.298 0.056 0.187 0.265 0.289 0.263 0.286 0.109 0.420** N =431 Errors (%) 0.344 0.391 0.256 0.412** 0.276 −0.093 0.050 0.247 −0.225 −0.300 −0.106 −0.155 0.313 0.113 0.150** N=431 Errors (%) 0.445* −0.025 0.282 0.238 0.280 0.014 0.295 0.337 0.286* 0.031 −0.176 0.025 0.257 −0.050 0.219** N=431 −0.623** N/D 0.034 N/D N/D N/D −0.070 N/D N/D −0.267 −0.148 N/D N/D N/D −0.396** N=149