Table 1 List of studies included in the ALE meta-analyses

Diekhof et al. 2009

Healthy: 4 male, 5 female, 24.4 years (S.D. 2.2)

Subtle changes in audio frequency

Detectable changes in audio frequency

9

1

WB_e

p < 0.001

Lawal et al. 2006

Irritable Bowel Syndrome: 10 female, Healthy: 10 female. 19–38 years

Rectal stimulation (bag inflated below perception threshold)

Rectal stimulation (bag inflated above perception threshold)

18

17

WB_b

p < 0.05

Phillips et al. 2004

Healthy: 5 males (grp.1), 29.5 years (S.D. 4.7) 5 male (grp. 2) 28.4 years (S.D. 6.2)

Covert angry and disgusted faces

Overt angry and disgusted faces

8

23

WB_b

p < 0.005

Prochnow et al. 2013

Healthy: 5 men, 7 women, 23.8 years (S.D. 3.0)

Covert facial expressions of happiness, anger, sadness

Overt facial expressions of happiness, anger, sadness

12

11

WB_e

p < 0.05 (2 foci at p < 0.01)

Sidhu et al. 2004

Irritable Bowel Syndrome: 8 female, Healthy: 8 female, 19–38 years

Rectal stimulation (bag inflated below perception)

Rectal stimulation (bag inflated at perception and above perception)

16

64

WB_b

p < 0.05

Duan et al. 2010

Healthy: 5 males, 13 females, 23.6 years (S.D. 1.3)

Covert surprised faces

18

41

WB_b

p < 0.001

Kouider et al. 2009

Healthy: 8 males, 8 female, 23 years (S.D. 2)

Covert famous faces

16

9

WB_e

p < 0.001

Smith et al. 2011

Healthy female, 29 years (range 19–53)

Rectal stimulation (bag inflated below perception)

14

13

WB_b

p < 0.001

Song et al. 2006

Irritable Bowel Syndrome: 12 female, Healthy: 12 female. 23 years (S.D. 0.3/S.D. 0.92)

Rectal stimulation (bag inflated below perception)

24

13

WB_b

p < 0.001

135

192

Diekhof et al. 2009

Healthy: 4 male, 5 female, 24.4 years (S.D. 2.2)

Subtle changes in audio frequency

Changes in audio frequency

9

27

WB_e

p < 0.001

Gillath & Canterberry, 2011

Healthy: 19 male. 20 female, 19.65 years (no avail S.D.)

Masked sexual images presented at 23 ms

Supraliminal masked sexual images presented at 524 ms

39

21

WB_e

p < 0.001

Lawal et al. 2006

Irritable Bowel Syndrome: 10 female, Healthy: 10 female. 19–38 years

Rectal stimulation (bag inflated below perception threshold)

Rectal stimulation (bag inflated above perception threshold)

18

25

WB_b

p < 0.05

Phillips et al. 2004

Healthy: 5 male (grp.1), 29.5 years (S.D. 4.7) 5 male (grp. 2) 28.4 years (S.D. 6.2)

Covert angry and disgusted faces

Overt angry and disgusted faces

8

32

WB_b

p < 0.005

Prochnow et al. 2013

Healthy: 5 men, 7 women, 23.8 years (S.D. 3.0)

Covert facial expressions of happiness, anger, sadness

Overt facial expressions of happiness, anger, sadness

12

11

WB_e

p < 0.05 (2 foci at p < 0.01)

Sidhu et al. 2004

Irritable Bowel Syndrome: 8 female, Healthy: 8 female, 19–38 years

Rectal stimulation (bag inflated below perception)

Rectal stimulation (bag inflated at perception and above perception)

16

136

WB_b

p < 0.05

Hall et al. 2010

Irritable Bowel Syndrome: 7 female, Healthy: 6 female, 30–40 years

Rectal stimulation (bag inflated above pain perception)

13

26

WB_e

p < 0.001

Kouider et al. 2009

Healthy: 8 males, 8 female, 23 years (S.D. 2)

Overt famous faces

16

8

WB_e

p < 0.001

Smith et al. 2011

Healthy female, 29 years (range 19–53)

Rectal stimulation (bag inflated above pain perception)

14

9

WB_b

p < 0.001

Song et al. 2006

Irritable Bowel Syndrome: 12 female, Healthy: 12 female. 23 years (S.D. 0.3/S.D. 0.92)

Rectal stimulation (bag inflated above pain perception)

24

20

WB_b

p < 0.001

169

315

Grand Total:

304

507