The problem with our sensory world – this “blooming, buzzing confusion” of sights, sounds and smells – is that we put so much faith in it. We believe that the world we experience the world as it is, and that our sensations are an accurate summary of reality.
But that’s a convenient illusion. In fact, it is the one illusion that makes every other perceptual illusion possible. Although we’re convinced that we’re living in an Ingres canvas – full of exquisite detail and verisimilitude – we actually inhabit a post-impressionist painting, rife with empty spaces and abstraction. It’s a world so full of ambiguities that it requires constant interpretation.
I’m most interested in the practical consequences of our sensory flaws. Let’s begin with this clever paper
, published earlier this year in Cognition. The study was led by Lars Hall, at Lund University. It was inspired by a 2005 study, led by Petter Johansson, that showed male subjects a pair of female faces. The subjects were asked to choose the face that they found more attractive. Then, the mischievous scientists used a “card trick” to reverse the outcome of the choice. Here’s where the results get a little sad: Less than 30 percent of subjects noticed that their choice had been changed. Our eyes might have preferences, but this doesn’t mean our mind can remember them.
In this latest study, Hall and colleagues sought to extend this phenomenon – it’s known as choice blindness – to the world of smell and taste. (The paper is called “Magic at the marketplace: Choice blindness for the taste of jam and the smell of tea”.) They asked 180 consumers at a supermarket to participate in a quick little experiment. (The scientists pretended to be “independent consultants con- tracted to survey the quality of the jam and tea assortment” in the retail store.) The consumers were told to focus on the taste of the jam and the smell of the tea, and were asked to pick their preferred product when given a variety of different samples. For instance, a participant might be asked to choose between Ginger and Lime jam, or Cinnamon-Apple and Grapefruit. If they were smelling teas, then they might be given a choice between Apple Pie versus Honey, or Pernod versus Mango.
At first glance, this seems like a ridiculous experiment. It’s hard to believe that, when asked to choose between Cinnamon-Apple and Grapefruit jam, I wouldn’t notice the difference. Or that, after choosing Mango tea over Pernod, I would fail to realize that I was actually being given Pernod.
And yet, that’s exactly what happened.
Jonah Lehrer is the author of How We Decide and Proust Was a Neuroscientist .