Laura Macchi

Who they are

Laura Macchi is first author, with Edoardo Zulato, of the 2021 Judgment and Decision Making paper on the pragmatics of number formats in the medical framing problem. The paper reports three studies, with 150, 180 and 430 participants, and its sample drew on medicine, statistics and lay students. Her work in this vault is the 2021 paper, which re-examines the surgery and radiation problem first published by McNeil and colleagues in 1982.

Key papers

Macchi and Zulato (2021), Judgment and Decision Making 16(3), 596-613. The paper examines the framing effect in the medical problem introduced by McNeil and colleagues in 1982, where people often favoured the risky option, surgery, in a survival frame and less often in a mortality frame. The authors argue that the pattern stems from the cumulative frequency format used to present the data, which people may misread as linear. Drawing on Gricean pragmatics, they suggest that the cumulative format violates conversational expectations, so people add figures sequentially and misjudge the outcomes.

Study 1, with 150 participants across medicine, statistics and lay students, replicated the original effect, and many participants in the mortality frame thought the numbers did not add up. Study 2, with 180 participants, compared formats: the cumulative format produced a framing effect, while the linear progression format did not, with about 73 and 71 per cent choosing surgery in the two frames. Study 3, with 430 participants, compared cumulative, linear progression and interval formats in the mortality frame. With the cumulative format 83 per cent chose radiation, while 68.5 per cent with the linear progression format and 59.1 per cent with the interval format chose surgery. About 52 per cent of the cumulative-format participants judged the data wrong, compared with about 11 per cent in the other formats.

Key ideas

The authors conclude that the reversed framing effect in this medical paradigm is not a true cognitive bias but a result of misleading communication, and that people understand the information better in linear progression and interval formats. They write that the formulation of a problem plays a relevant role in how the decision task is represented.

---