When assessing the likelihood of an event, human judgment is often inconsistent with the rules inherent in standard probability theory. For example, the judged probability of an event can be heavily influenced by the alternatives that are explicitly presented. Tversky and Koehier (1994) attempted to account for this phenomenon by arguing that probability judgments are made by comparing the amount of cognitive support one holds in favour of the event in question relative to all other possibilities. They suggested that different descriptions of the same event elicit different amounts of support resulting in different probability ratings. In addition to the role played by explicitly considered alternatives, the present paper suggests that people are also sensitive to the influence of alternatives that are not considered explicitly. We present the term "implied numerosity' in an attempt to indicate that probability ratings are influenced by a general impression of the number of potential alternatives that exist. Systematic differences in probability estimations may result from systematic changes in the perceived size of the category being evaluated.

Objective

Receptiveness to interprofessional feedback, which is important for optimal collaboration, may be influenced by 'in-group or out-group' categorisation, as suggested by social identity theory. We used an experimental design to explore how nurses and resident physicians perceive feedback from people within and outside their own professional group.

Methods

Paediatric residents and nurses participated in a simulation-based team exercise. Two nurses and two physicians wrote anonymous performance feedback for each participant. Participants each received a survey containing these feedback comments with prompts to rate (i) the usefulness (ii) the positivity and (iii) their agreement with each comment. Half of the participants received feedback labelled with the feedback provider's profession (two comments correctly labelled and two incorrectly labelled). Half received unlabelled feedback and were asked to guess the provider's profession. For each group, we performed separate three-way anovas on usefulness, positivity and agreement ratings to examine interactions between the recipient's profession, actual provider profession and perceived provider profession.

Results

Forty-five out of 50 participants completed the survey. There were no significant interactions between profession of the recipient and the actual profession of the feedback provider for any of the 3 variables. Among participants who guessed the source of the feedback, we found significant interactions between the profession of the feedback recipient and the guessed source of the feedback for both usefulness (F1,48 = 25.6; p < 0.001; η(2) = 0.35) and agreement ratings (F1,48 = 8.49; p < 0.01; η(2) = 0.15). Nurses' ratings of feedback they guessed to be from nurses were higher than ratings of feedback they guessed to be from physicians, and vice versa. Among participants who received labelled feedback, we noted a similar interaction between the profession of the feedback recipient and labelled source of feedback for usefulness ratings (F1,92 = 4.72; p < 0.05; η(2) = 0.05).

Conclusion

Our data suggest that physicians and nurses are more likely to attribute favourably perceived feedback to the in-group than to the out-group. This finding has potential implications for interprofessional feedback practices.