Table 1.
Basic characteristics of meta-analyzed studies and their interventions. Binary and categorical variables are reported as “count (percentage)”. Continuous variables are reported as “median (first quartile, third quartile)”.
| Characteristic | Number of studies (%) or median (Q1, Q3) |
|---|---|
| Country | |
| Canada | 1 (1%) |
| China | 2 (2%) |
| Czech Republic | 2 (2%) |
| Ecuador | 1 (1%) |
| France | 3 (3%) |
| Germany | 1 (1%) |
| India | 3 (3%) |
| Netherlands | 1 (1%) |
| Portugal | 2 (2%) |
| Scotland | 2 (2%) |
| USA | 37 (37%) |
| USA, Canada | 2 (2%) |
| Not reporteda | 43 (43%) |
| Percent male subjects | 43 (36.1, 51.7) |
| Not reported | 4 (4%) |
| Average age (years) | 33.7 (21.9, 35.4) |
| Not reported | 9 (9%) |
| Student recruitment | |
| Not undergraduates | 77 (77%) |
| General undergraduates | 10 (10%) |
| Social sciences undergraduates | 3 (3%) |
| Mixed | 10 (10%) |
| Intervention had text | |
| Yes | 83 (83%) |
| No | 14 (14%) |
| Not reported | 3 (3%) |
| Intervention had visuals | |
| Yes | 62 (62%) |
| No | 36 (36%) |
| Not reported | 2 (2%) |
| Intervention had graphic content | |
| Yes | 61 (61%) |
| No | 37 (37%) |
| Not reported | 2 (2%) |
| Intervention used mind attribution | |
| Yes | 65 (65%) |
| No | 28 (28%) |
| Not reported | 7 (7%) |
| Intervention used social norms | |
| Yes | 29 (29%) |
| No | 62 (62%) |
| Not reported | 9 (9%) |
| Intervention identified a named victim | |
| Yes | 21 (21%) |
| No | 70 (70%) |
| Not reported | 9 (9%) |
| Intervention depicted pets | |
| Yes | 32 (32%) |
| No | 60 (60%) |
| Not reported | 8 (8%) |
| Intervention gave implementation suggestions | |
| Yes | 29 (29%) |
| No | 61 (61%) |
| Not reported | 10 (10%) |
| Intervention described animal welfare only | |
| Yes | 52 (52%) |
| No | 44 (44%) |
| Not reported | 4 (4%) |
| Intervention was personally tailored | |
| Yes | 2 (2%) |
| No | 98 (98%) |
| Not reported | 0 (0%) |
| Intervention’s recommendation | |
| No recommendation | 43 (43%) |
| “Reduce consumption” | 13 (13%) |
| “Go vegetarian” | 9 (9%) |
| “Go vegan” | 7 (7%) |
| Mixed recommendation | 24 (24%) |
| Not reported | 4 (4%) |
| Intervention’s duration (minutes) | 1.5 (1, 5.88) |
| Not reported | 2 (2%) |
| Outcome category | |
| Consumption | 96 (96%) |
| Purchase | 4 (4%) |
| Length of follow-up (days) | 0 (0, 32.5) |
| Not reported | 1 (1%) |
| Source of statistics | |
| Data from author | 19 (19%) |
| Paper | 28 (28%) |
| Public data | 53 (53%) |
a:
There was a high proportion of missing data regarding studies’ countries because we coded country as missing for online studies (e.g., conducted on Amazon Mechanical Turk) that did not specifically state whether they used geographical restrictions when recruiting subjects.