Table I.
Characteristics of the included studies
| Article/Ref. # | Imaging modality | ASD | NC | Task | Contrast | # foci | |||
|---|---|---|---|---|---|---|---|---|---|
| n | Age M (SD)* | n | Age M (SD) | NC | ASD | ||||
| Social (24) | |||||||||
| Ashwin et al., 2006** (144) | fMRI | 13 | 31.2 (9.1) | 13 | 25.6 (5.1) | Facial processing | Faces vs. scrambled faces | 5 | 1 |
| Hubl et al., 2003** (145) | fMRI | 10 | 27.7 (7.8) | 10 | 25.3 (6.9) | Facial processing | Faces vs. scrambled faces | 4 | 4 |
| Schultz et al., 2000** (20) | fMRI | 14 | 23.8 (12.4) | 14 | 21.7 (7.2) | Facial processing | Faces vs. objects | 1 | 1 |
| Bird et al., 2006** (146) | fMRI | 16 | 33.3 (12.1) | 16 | 35.3 | Facial processing | Faces vs. houses | 5 | 5 |
| Deeley et al., 2007** (147) | fMRI | 9 | 34 (10) | 9 | 27 (5) | Facial processing | Neutral faces vs. fixation | 21 | 25 |
| Kleinhans et al., 2008** (148) | fMRI | 19 | 23.5 (7.8) | 21 | 25.1 (7.6) | Facial processing- one back task | Neutral faces vs. houses | 1 | 3 |
| Koshino et al., 2007** (149) | fMRI | 11 | 24.5 (10.2) | 11 | 28.7 (10.9) | Facial processing n-back WM | n-back face task vs. fixation | 15 | 9 |
| Dichter et al., 2006** (150) | fMRI | 14 | 22.9 (5.2) | 15 | 23.2 (5.7) | Flanker gaze task | Congruent vs. Incongruent gaze | 8 | 2 |
| Dapretto et al., 2005# (151) | fMRI | 10 | 12.05 (2.5) | 10 | 12.38 (2.2) | Imitating facial expressions | Face Imitation vs. rest | 36 | 16 |
| Wang et al., 2004# (152) | fMRI | 12 | 12.2 (4.8) | 12 | 11.8 (2.5) | Facial emotion processing | Faces (angry/fearful) vs. geometric forms | 10 | 11 |
| Hall et al., 2003# (153) | PET | 8 | 20–33 | 8 | n.a | Facial emotion processing | Emotion vs. gender | 6 | 7 |
| Critchley et al., 2000# (22) | fMRI | 9 | 37 (7) | 9 | 27 (7) | Facial emotion processing | Emotional vs. neutral faces | 6 | 3 |
| Pelphrey et al., 2007# (154) | fMRI | 8 | 24.5 (11.5) | 8 | 24.1 (5.6) | Facial emotion processing | Dynamic vs. static emotional face | 6 | 1 |
| Pelphrey et al., 2005# (155) | fMRI | 10 | 23.2 (9.9) | 9 | 23.4 (5.8) | Intentional eye gaze processing | Congruent vs. incongruent eye gaze | 7 | 4 |
| Pierce et al., 2004# (156) | fMRI | 7 | 27.1 (9.2) | 9 | (16–40) | Facial processing | Familiar vs. stranger faces | 9 | 4 |
| Pinkham et al., 2008# (157) | fMRI | 10 | 24.08 (5.71) | 12 | 27.08 (3.99) | Trustworthiness face task | Trustworthy faces vs. baseline | 6 | 6 |
| Baron-Cohen et al., 1999# (16) | fMRI | 6 | 26.3 (2.1) | 12 | 25.5 (2.8) | Inferring mental states/eye | Emotion vs. gender | 53 | 29 |
| Castelli et al., 2002 (158) | PET | 10 | 33 (7.6) | 10 | 25 (4.8) | Inferring mental states/ animated shapes | ToM animation vs. random animation | 10 | 10 |
| Happe et al., 1996 (13) | PET | 5 | 24 | 6 | 38 | Story comprehension | Tom story vs. unconnected sentences | 4 | 4 |
| Gervais et al., 2004 (159) | fMRI | 5 | 25.8 (5.9) | 8 | 27.1 (2.9) | Voice processing | Vocal vs. non-vocal sounds | 6 | 0 |
| Wang et al., 2006 (160) | fMRI | 18 | 11.9 (2.8) | 18 | 11.9 (2.3) | Judging sentences sarcasm | Sarcastic sentences vs. rest | 16 | 19 |
| Wang et al., 2007 (15) | fMRI | 18 | 12.5 (2.9) | 18 | 11.8 (1.9) | Cartoon irony/sarcasm task | Ironic cartoons vs. non-ironic cartoons | 35 | 32 |
| Mason et al., 2008 (161) | fMRI | 18 | 26.5 | 18 | 27.4 | Inference reading comprehension task | intentional inference vs. fixation | 13 | 20 |
| Williams et al., 2006 (162) | fMRI | 16 | 15.4 (2.24) | 15 | 15.5 (1.6) | Action imitation task | Imitation vs. action execution | 7 | 4 |
| Non-social (15) | |||||||||
| Ring et al., 1999 (39) | fMRI | 6 | 26.3 (2.1) | 12 | 25.5 (2.8) | Embedded figure task | Task vs. fixation | 10 | 10 |
| Manjaly et al., 2007 (38) | fMRI | 12 | 14.4 (2.7) | 12 | 14.3 (2.7) | Embedded figure task | Embedded figure task vs. control task | 2 | 4 |
| Lee et al., 2007 (37) | fMRI | 12 | 13.5 (1.6) | 12 | 13.8 (1) | Embedded figure task | Embedded vs. matching task | 11 | 3 |
| Just et al., 2007 (131) | fMRI | 18 | 27.1 (11.9) | 18 | 24.5 (9.9) | Tower of London task | Hard vs. easy condition | 13 | 19 |
| Kennedy et al., 2006 (114) | fMRI | 15 | 25.5 (9.6) | 14 | 26.1 (8) | Stroop task | Number vs. rest | 8 | 8 |
| Koshino et al., 2005 (115) | fMRI | 14 | 25.7 | 13 | 29.8 | N-back working memory task | n-back task vs. fixation | 24 | 24 |
| Schmitz et al., 2006 (163) | fMRI | 10 | 38 (8) | 12 | 39 (9) | Go/No-Go | No-Go vs. go | 11 | 6 |
| Haist et al., 2005 (164) | fMRI | 8 | 23.4 (11.4) | 8 | 25.6 (3.8) | Spatial attention task | Spatial target vs. null | 40 | 1 |
| Belmonte et al., 2003 (165) | fMRI | 6 | 32.7 (9.8) | 6 | 27.2 (4.4) | Visual spatial attention task | Task vs. fixation | 7 | 4 |
| Schmitz et al., 2008 (116) | fMRI | 10 | 37.8 (7) | 10 | 38.2 (6) | CPT task with monetary incentive | Rewarded vs. non-rewarded stimuli | 5 | 4 |
| Gomot et al., 2006 (166) | fMRI | 17 | 10.37 (1.52) | 14 | 10.87 (1.47) | Auditory change detection | Novel vs. standard sound | 17 | 17 |
| Gaffrey et al., 2007 (72)$ | fMRI | 10 | 26.1 (10.5) | 10 | 25.3 (9.8) | Semantic category | Semantic vs. perceptual task | 14 | 13 |
| Harris et al., 2006 (71) $ | fMRI | 14 | 36 (12) | 22 | 31 (9) | Single word lexical semantic processing | Concrete vs. abstract words | 8 | 4 |
| Just et al., 2004 (70) $ | fMRI | 17 | n.a. | 17 | n.a. | Sentence comprehension | Sentence vs. fixation | 8 | 10 |
| fMRI | 8 | 28.4 (8.9) | 8 | 28.5 | Paced finger tapping | Tapping vs. rest | 11 | 12 | |
The 39 studies included in the meta-analysis were subdivided into a social and non-social task-class based on the paradigm used. Overall a total of 359 and 479 foci were included for the ASD and the NC group, respectively.
*
M age (SD) = mean age of subjects ± standard deviation are reported if available in published article. ASD =autism spectrum disorders, fMRI = functional magnetic resonance imaging, NC = neurotypical controls, n.a.= not available , PET = positron emission tomography, Ref = reference #; Tom = Theory of Mind.
**
grouped as face form perception study;
#
grouped as facial emotional/intentional expression studies; these two study groups formed the face processing study group for post-hoc analyses.
$
these studies were excluded in the secondary analysis of non-socials studies of executive processes only.