Table 1.

Internal consistency and substantial variability in human brain and behavior

DatasetAge: range, mean (SD)Number of characteristics in analysis of internal consistency (number of characteristics assessed for sex/gender differences)Percent of brains/individuals with substantial variability: both male-end and female-end featuresPercent of brains/individuals with internal consistency: only female-end (F), only intermediate (I), or only male-end (M) (all, ♂, ♀)Average (SD) percent of features at the female-end (F) and male-end (M) zones (♂, ♀) and Cohen’s d of the sex/gender difference
First sample, VBM♂: 18–79,10 (116)All: 35%F: 0.4, 0.0, 0.6%F: 13 (17), 33 (25)
31.5 (12.0)0.70 < |d| ≤ 0.84♂: 35%I: 3.6, 3.6, 3.6%d = 0.95*
♀: 18–75all P < 0.0001♀: 34%M: 2.0, 5.0, 0%M: 33 (30), 10 (15)
28.9 (10.4)d = −0.96*
1000, VBM♂: 18–74,10 (116)All: 39%F: 0.1, 0.0, 0.2%F: 15 (19), 33 (25)
28.8 (14.3)0.51 < |d| ≤ 0.69♂: 37%I: 2.3, 3.3, 1.6%d = 0.83*
♀: 18–78,all P < 0.0001♀: 40%M: 2.9, 5.3, 1.2%M: 33 (31), 17 (23)
26.8 (10.4)d = −0.61*
1000, VBM 18–26 subsample♂: 18–26,9 (116)All: 53%F: 0.3, 0.4, 0.2%F: 16 (19), 33 (24)
21.5 (1.9)0.46 < |d| ≤ 0.60♂: 47%I: 1.3, 0.8, 1.6%d = 0.79*
♀: 18–26,all P < 0.0001♀: 55%M: 0.8, 1.2, 0.5%M: 33 (25), 19 (20)
21.5 (2)d = −0.62*
NKI, SBA, cortical thickness7 (68)All: 24%F: 4.5, 2.0, 5.9%F: 21 (27), 33 (29)
♂: 13–83,0.41 < |d| ≤ 0.56♂: 21%I: 2.2, 2.0, 2.4%d = 0.42*
41.0 (20.3)all P < 0.002♀: 26%M: 3.7, 8.0, 1.2%M: 33 (34), 15 (22)
♀: 12–85,d = −0.64*
NKI, SBA, volume48.7 (17.4)12 (168)All: 23%F: 1.5, 0.0, 2.3%F: 9 (16), 33 (27)
0.94 < |d| ≤ 1.04♂: 25%I: 3.3, 2.9, 3.6%d = 1.05*
all P < 0.0001♀: 21%M: 0.7, 1.9, 0.0%M: 33 (27), 16 (15)
d = −1.13*
DTI fractional anisotropy11 (116)All: 25%F: 2.2, 0.0, 4.3%F: 9 (15), 33 (33)
♂: 17–43,0.73 < |d| ≤ 1.05♂: 29%I: 2.9, 2.9, 2.9%d = 0.93*
24.8 (4.6)all P < 0.0001♀: 20%M: 0.7, 1.4, 0.0%M: 33 (29), 12 (20)
♀: 18–57,d = −0.83*
DTI connectivity26.3 (7.0)7 (4,005)All: 48%F: 0.0, 0.0, 0.0%F: 14 (16), 33 (18)
0.66 < |d| ≤ 0.96♂: 52%I: 0.7, 0.0, 1.4%d = 1.15*
all P < 0.00017§♀: 43%M: 0.0, 0.0, 0.0%M: 33 (20), 9 (11)
d = −1.53*
MADICS♂: 20–23, 21.6 (0.7)7 (31)All: 59%F: 0.0, 0.0, 0.0%F: 17 (15), 32 (18)
♀: 20–23, 21.3 (0.6)0.43 < |d| ≤ 0.77♂: 64%I: 1.8, 1.1, 2.1%d = 0.92*
all P < 0.0001♀: 56%M: 0.0, 0.0, 0.0%M: 32 (17), 13 (14)
d = −1.23*
ADD Health♂: 18–28, 22.4 (1.9)8 (26)All: 70%F: 0.0, 0.0, 0.0%F: 27 (16), 45 (19)
♀: 18–28, 22.1 (1.9)0.41 < |d| ≤ 0.57♂: 81%I: 0.1, 0.2, 0.03%d = 1.04*
all P < 0.0001♀: 62%M: 0.0, 0.0, 0.0%M: 29 (17), 13 (13)
d = −1.01*
Carothers & Reis’ data21.15 (7.68)10 (10)All: 55%F: 0.4, 0.0, 0.6%F: 11 (11), 48 (20)
1.0 < |d| ≤ 2.02♂: 65%I: 0.4, 0.9, 0.0%d = 2.27*
all P < 0.0001♀: 48%M: 0.4, 0.9, 0.0%M: 41 (17), 8 (10)
d = −2.42*
  • ♂, males; ♀, females.

  • * Statistically significant difference, P < 0.0001.

  • 1000 = 1000 Functional Connectomes Project.

  • If we were to include only regions with |Cohen’s d| > 0. 51 as in the analysis of the entire sample, only three regions would have been included.

  • § Of the seven connections included, two were statistically significant and five approached significance.

  • Note the deviation from 33%, which reflects the inability to define the cutoff at 33% for some of the variables included in the analysis (see Methods for details).