When recruiters are looking to evaluate a prospect in an executive search, ultimately what they're looking for is to answer the question,
"Should we hire this person?"
And really you can boil down many decisions about other people into a relatively simple yes or no, not because there aren't complicated factors involved in the decision, but because it's hard to maintain any really nuanced attitude.
Still, while we're looking for a simple answer to a simple question, we're also hoping to arrive at that answer through a fairly inclusive and detailed analysis. You don't want to base your recruiting decisions on something as unpredictable as gut instinct, but rather on a thorough analysis of a candidate's qualifications across a broad range of potential responsibilities.
Unfortunately, it turns out our brains aren't quite as interested in trying to rate candidates across a wide range of independent characteristics. Instead, a person tends to associate others with almost all good or all bad qualities, depending largely on the nature of her first impression - a habit psychologists have dubbed the "halo effect."
The Economist explains that the halo effect has actually been documented as far back as 1920, when psychologist Edward Thorndike examined military officers' assessments of their troops. Miraculously, the soldiers who showed the most character and leadership potential were also the fittest and most intelligent.
This tendency has been backed up repeatedly over time, and what's more, psychologists have shown that these initial impressions are indeed exceedingly hard to change - showing just how true the old advice really is.
How this relates to you
In a Harvard Business Review article, two consultants took the obvious step and applied this idea to hiring and staffing, showing how often recruiters and executives make questionable hiring decisions based on the afterglow from a good impression.
The scary thing about this for recruiters, though, is that these results show up on surveys of specific attributes, showing how much his perceptions can be influenced by extraneous information.
How to beat the halo
So if you're going to avoid making these unjustified hiring decisions, you have to take some more unusual measures. Surveys are still a good starting point, but one possible fix would be to include specific justifications of the various ratings you give people on any given attribute.
Other possibilities include trying to make direct comparisons between more than two candidates on various attributes. This way you won't be able to fall into the good/bad dichotomy.