Why we choose the things we do is a fascinating subject as it gives insight into the irrationality of our choices.  It's well known for instance that how you price things can impact upon our perception of other products around them.  For instance if there are three milkshakes on offer, a small one, a medium one and a large one, if the large one is very large/expensive then it makes us buy the middle one.  This is often used to minipulate our behaviour, with retailers using the extreme product to nudge us towards buying the version they want us to buy, ie the one with highest profit margin.

Does the same apply however if products are arranged physically in front of us?  New research looking into the topic found that when products are arranged left to right, we seem to gravitate towards the middle product most of the time, something known as the Centre Stage Effect.

The research team showed participants a questionnaire with 17 questions.  Each question contained five pictures of the same item, with each set of pictures arranged in a horizontal row.  Remember that each picture is of the same product.  Which did they prefer do you think?  You guessed it, the middle picture was favoured most of the time.  Interestingly, when picking out the picture they didn't like, there was no such bias.

The difference wasn't huge, with the middle picture selected 23% of the time, so slightly above the 20% you'd expect if people just chose at random, but interesting nonetheless.

They tested the hypothesis again in a second study, with the pictures this time arranged vertically rather than horizontally.  The orientation didn't seem to matter however, with the central picture chosen more often than the rest.

Finally the researchers tested their theory using real objects, which in this case were identical pairs of socks.  The socks were pinned to a piece of cardboard in a vertical line, and participants were asked to pick their favourite.  Once again the middle pair were chosen more often than they should have been.

So, how does this translate to the real world?
 

"If item location influences preference during the millions of purchasing choices that occur every day, it will be exerting a substantial influence on consumer behaviour," the researchers said. "Moreover, choices from a range of options are made in many other contexts (e.g. legal and occupational), and it remains to be investigated whether the central preference remains with other formats and whether it extends to other types of decision."

Which got me thinking about how this might apply to the web.  An obvious example is Google Adwords.  There you have a series of ads arrayed vertically.  Do we tend to pick the middle option more often than the rest?  Click through data would suggest not, BUT, Wharton research does show that adverts in the middle convert much more than adverts in the top spots.  To be fair however they suggested this is more likely due to comparison shoppers clicking on a few ads rather than any underlying cognitive bias.

Interesting nonetheless though.