exBEERiment | The Impact of Expectation on Perception

Author: Marshall Schott

There are things known and there are things unknown, and in between are the doors of perception.
~ Aldous Huxley ~

Perception is a fascinating subject to me, something I spent years studying and pondering in musty university libraries. I recall times sitting in the skybridge at Western Washington University, creepily gazing down upon passing students doing their own things, wondering how they were perceiving things in that precise moment. As someone obsessed with the human condition, I came to my own private conclusion that perception is… everything. Our beliefs, habits, moods, understanding of self and others, everything is driven by how we perceive our world. I also came to understand, at least through the subjective filters of my own mind, that us confusingly complicated humans have yet to evolve into creatures with perfect perception. So, what does this have to do with beer and brewing?

Since I began conducting these exBEERiments, I’ve always wondered the extent to which a taster’s expectation of difference impacts their perception of the beers. I use a triangle test for data collection, which is a type of discrimination testing used for sensory evaluation that involves a taster receiving 3 portions of beer with 1 being different than the others, then they’re asked to identify the different one. The actual difference between the samples is limited to a single variable, so the perceptible difference can be pretty subtle. Statistically speaking, it’s assumed 1/3 of tasters would randomly guess the correct beer, thus findings aren’t interpreted as significant unless a good portion of tasters correctly choose the different beer (about 66% for our purposes). Interestingly, the majority of exBEERiment results have not yielded significant results, suggesting the variables I’ve tested don’t seem to have a huge impact. Many readers of these results have expressed interest in another type of test, one containing a slight element of deception, an exBEERiment I’ve been curious to perform for awhile.

| PURPOSE |

To evaluate the impact one’s expectation of difference has on their perception of actual differences between 3 beers… that are exactly the same.

| METHOD |

For extensive brew day notes, refer to the recent Mexico vs. Germany post comparing WLP940 to WLP830, as I used the former alone for the present exBEERiment. Each taster, all blind to the nature of the exBEERiment, was provided 3 samples in a private setting with limited distractions. The beers were poured first then the taster was asked to enter the tasting area. I used colors to identify each sample, they corresponded to the 3 selections in the survey used to collect data.

Maybe you noticed one of the options, the only accurate one in this case, is No detectable differences. This is the option we would expect tasters to select given the fact all 3 beers were exactly the same, filled from the same exact keg. Let’s not forget, though, that every taster was cognitively primed to expect one of the beers to be different.

| RESULTS |

Of the 10 people who participated in this exBEERiment, only 1 perceived no detectable difference between the beers. For what it’s worth, this single “correct” person is the only participant who isn’t a craft beer nerd and/or homebrewer, he’s my humble Coors Light drinking neighbor. Make of that what you will.

I’d caution anyone against being too presumptuous after reading these results, chances are you would have been wrong, too. The participants in this exBEERiment included award winning homebrewers, Cicerone certified beer servers, and a professional brewer. Leave it to the naive to jump to the simplest conclusion. The results of this exBEERiment appear to support the notion that one’s perception is influenced by their expectations, covert as it may be. As much as we like to think we’re in full control of our faculties, this simply does not appear to be the case. I experienced mixed emotions when sharing the nature of this exBEERiment with participants, a sort of sadistic shame, particularly when they were so convinced the beer they selected was different. The shit we stir for science.

More than anything, these findings support something we all know, that perception is not perfect and that despite all of our palate training efforts, we can still fall victim to our feeble minds. Does this mean sensory evaluation is a poor way to measure differences? Absolutely not! This is why we have measures of statistical significance. If 7+ of 10 tasters (p<0.05), for example, accurately select the different beer, we can trust the tasters selections were less than chance and be confident there was an actual difference.

This was a fun exBEERiment for me. Thanks to all the killer brewers and tasters who participated, please don’t hold it against me…

UPDATE: For those who get off on this type of stuff, I highly recommend you pick up Denny Conn’s and Drew Beechum’s newest book, Experimental Homebrewing, which has a section dedicated to tasting objectivity.

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| Read More |

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 7 Considerations for Making Better Homebrew
 List of completed exBEERiments 
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How-to: Make a lager in less than a month 

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