Two experiments were executed to study how persons test hypotheses about others. Experiment 1 demonstrated that subjects can be sensitive to contextually presented alternatives to a given hypothesis. Subjects who addressed the hypotheses that an interviewee was an architect or a painter selected different information than did those who addressed the hypotheses that the interviewee was an architect or a computer engineer. In both cases, subjects' informational choices appeared guided by the principle of diagnosticity. Notably, they predominantly selected information whose diagnostic value with respect to the pertinent hypothesis-alternative pair was high rather than low. Experiment 2 demonstrated that subjects' sensitivity to a contextually mentioned alternative (architect) to a given target hypothesis (painter) may be affected by their motivational orientation. Subjects with a high need for openness (as manipulated by high fear of invalidity) and low need for closure were more likely to seek diagnostic information demarcating the hypothesis from the alternative than subjects with a high need for closure and low fear of invalidity. Thus, the present research highlights the subjective determinants of information diagnosticity: It suggests that diagnosticity may depend on the cognitive context of hypothesis testing (the type of alternatives juxtaposed to a target hypothesis), and on individuals' epistemic motivations, which may affect their sensitivity to contextually suggested hypotheses.