Table 6: Treatment effects.
| Saw text only | Saw text + Whale | Saw text + Photo | Saw photo only | p-value for test of equal means | Overall means (std. dev.) | |
| Changes in general attitude and belief variables | ||||||
| Individual actions matter^ | 0.07* | 0.11*** | 0.12* | 0.17*** | 0.35 | -2.38 (0.74) |
| Personal responsibility | 0.19*** | 0.23*** | 0.23*** | 0.1 | 0.3 | 3.26 (1.06) |
| NEP-based index | 0.01 | 0.07* | 0.13** | 0.03 | 0.09 | -0.75 (0.82) |
| Changes in beliefs about plastic pollution | ||||||
| Causes litter | 0.06 | 0.13*** | 0.24*** | 0.01 | 0 | 4.02 (0.87) |
| Causes landfill pollution | 0.07* | 0.14*** | 0.08 | 0.07 | 0.48 | 4.12 (0.84) |
| Causes ocean pollution | 0.27*** | 0.23*** | 0.20*** | 0.09 | 0.03 | 4.08 (0.89) |
| Changes in components of NEP-based index | ||||||
| Abuse^ | 0 | 0.19*** | 0.16* | 0.13 | 0.05 | -2.13 (1.09) |
| Spaceship^ | 0 | 0.01 | 0.12 | 0.02 | 0.61 | -1.72 (1.19) |
| Balance of nature^ | 0.07 | 0.06 | 0.21** | 0.11 | 0.41 | -1.83 (1.09) |
| Crisis exaggerated | -0.02 | 0.02 | 0.03 | -0.15 | 0.35 | -0.69 (1.29) |
Each row represents a separate OLS regression.
^Reverse coded; *p < 0.05; **p < 0.01; ***p < 0.001 for test of zero means.