A large part of conversion optimization is figuring VP Security Email List out what to test, and we usually do that through a variety of research methods – user testing, usability testing, surveys, etc.

Anything that requires users to respond to a questionnaire more than a few questions long may suffer from bias due to Serial Position Effect.

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As Jeff Sauro, founder of MeasuringU, wrote:

Jeff Sauro:

“In usability testing, this [Serial Position Effect] is most commonly seen with tasks and product order.

Users typically perform worse on their initial tasks (as they get accustomed to the testing situation and being observed). When testing multiple interfaces or products, the most recently used product may have more salience in the user’s mind when they are asked to select their preference.

The best way to minimize primacy and recency effects is to alternate the presentation order of the tasks and products.”

It’s similar with customer surveys. As users begin to “learn” a survey, they tend to lead with answers that they believe will reach a desired outcome. Essentially, they’re trying to guess at the goal of the survey and they answer accordingly.

A similar bias to be aware of while designing longer surveys is the bias of central tendency. Fatigued, respondents begin to default to the mean score on any kind of Likert or Semantic Differential-type scale.

To mitigate the effects of both Serial Position Effect and Error of Central Tendency, the answer is simple: just mix up the questions for each respondent. Most survey tools have this capability.


Primacy and Recency Effects are quite strong influencers of human behavior. Thing is, they are not clear-cut, and there’s no silver bullet way to utilize them. The basic premise stands though:

We remember (and usually prefer things) that are presented first, as well as most recently. Things in the middle tend to be forgotten or lost in the noise.

Therefore, place things that deserve emphasis (links, articles, products, pricing plans) first or last to emphasize them on your site. Don’t assume that this will give you a lift, of course – test it for yourself. But know that our memories favor the first and last items in a sequence, and optimize with that knowledge in mind.

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