Assessing a partner: what an overall impression can distort
Choosing a supplier or research partner requires distinguishing between qualities that do not necessarily go together. The management question is specific: how can we prevent a favourable impression during an interview from also determining assessments of capabilities that require separate evidence?
What the literature establishes
Edward Thorndike (1920, Journal of Applied Psychology) described an error in assessments of people: ratings of different qualities were excessively interrelated. He interpreted this as the influence of an overall impression on specific judgements, now widely known as the halo effect. For a manager, the risk is treating several favourable ratings as independent confirmations when they may stem from a single impression.
An impression that changes specific judgements
Richard Nisbett and Timothy Wilson (1977, Journal of Personality and Social Psychology) showed students an instructor who appeared either warm or aloof, depending on the version. This manipulation changed their assessments of characteristics such as his appearance, mannerisms and accent. Participants generally did not recognise the influence of their overall impression on these specific assessments.
The premature conclusion
One might conclude that all interpersonal impressions should be excluded and decisions based solely on documents. These studies do not justify that rule: the quality of interaction can be a relevant criterion when cooperation is part of the assignment. The distinction is to assess it in its own right, rather than treating it as evidence of technical competence or operational reliability. (our executive and employee training programmes)
What the evidence cannot guarantee
Historical observations of personal assessments and the experiment involving students do not directly measure the quality of corporate supplier selection. Nor do they demonstrate that a multi-criteria assessment form is enough to neutralise the halo effect: several boxes can capture the same impression under different headings. A consistent assessment is therefore not necessarily a well-supported one.
A practical check in Fribourg
Within SHR’s « Prise de décision » programme, an exercise applicable in Fribourg would compare document-based assessments with subsequent post-interview assessments of an agrifood supplier or a partnership between bilingual industry and the university sector. For each technical criterion, the team would record supporting evidence before the discussion, then any rating change and the new information motivating it, using a shared French-German assessment form. The indicator would be the proportion of technical rating changes with no new supporting evidence recorded: a documented signal for review, not automatic proof of bias. To go further: explore the Decision-making training in Fribourg, or browse our executive and employee training programmes in Switzerland.
In pictures: Decision-making in Fribourg
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