2.2. Results and Discussion Ratings of both the agents’ responsibility and causality depended qualitatively on the rejected choice. The conditional probability of the desired outcome the actual choice was always .5, but participants’ evaluation of this choice varied with the conditional probability of the same outcome given the rejected option. Responsibility and causality ratings were highest (M = 6.18 on a 0-to-10 scale) when the probability of the actual choice was greater than that of the rejected choice (PACT > PALT) and lowest (M = 4.90) when the probability of the actual choice was less than that of the rejected choice (PACT < PALT). However, the magnitude of the difference between PALT and PACT had no further effect on judgments, consistent with an optimality strategy. Because there was no interaction between question type and PALT [F(4,372) = 0.76, p = .55, ηp2 < .01], we collapsed across responsibility and causality judgments in conducting pairwise comparisons for adjacent PALT values. Figure 1 graphs these mean ratings and their standard errors. These comparisons revealed a significant difference between the .3 condition (where Angie’s actual decision was optimal) and the .5 condition (where no uniquely optimal decision existed, since PACT also was .5) [t(94) = −2.74, p = .007, d = −0.28, BF10 = 2.9]. However, there was evidence against a difference between adjacent optimal conditions [for the .1 condition vs. the .3 condition, t(94) = 1.21, p = .23, d = 0.12, BF01 = 5.99] and between adjacent suboptimal conditions [for the .7 vs. .9 conditions, t(94) = −0.04, p = .86, d = −0.02, BF01 = 12.16]. Finally, the evidence was equivocal with respect to the difference between the .5 and .7 conditions [t(94) = 2.03, p = .029, d = 0.23, BF01 = 1.14]. Because PACT = .5, there was no optimal choice in the .5 condition, and the agent chose suboptimally in the .7 condition. Thus, if only optimality matters, one would expect no difference between these conditions, but if
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