Personality and the Senses

When people think of Psychology, one of the first words that usually pop-out is the term personality. In this case, why not connect this concept with sensory perception? Luckily that is exactly what Ilona Croy and her team did in their 2010 paper entitled "Agreeable Smellers and Sensitive Neurotics - Correlations among Personality Traits and Sensory Thresholds". In their research they investigated on several of the more common senses such as smell, touch, and taste and one other less common, which is trigeminal (I would expound on these later). Generally, their study showed that agreeable people tend to have a better sense of smell, significantly enhanced trigeminal sensitivity in neurotic people, and an enhanced pain tolerance in highly conscientious people.

The personality dimensions of NEO-PI were used to determine the correlations between personality traits and sensory thresholds. It is a scale crafted by Paul Costa and Robert McCrae back in the 1970s when they were researching on how personality changes with age (Burger, 2011). The NEO-FFI that was used in the research conducted by Croy and her coworkers is an updated, shortened version of the original NEO-PI. It still consists of the five dimensions - Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism and their respective facets.

OCEAN and Facets

As for the senses studied by the researchers, they focused on chemosensory perception like olfactory, gustatory, and trigeminal. Olfactory is the sense of see while gustatory is for taste perception. Trigeminal, on the other hand, is a less common chemosensory channel that is closely associated with the perception of pain and temperature information in the skin (Purves, Augustine, Fitzpatrick, Hall, La Mantia, & White, 2012). More generally, it is responsible for the burning/stinging sensation typically felt when eating spicy foods or when detecting fires.

In the actual experiment, the researchers initially asked each participant to answer the NEO-FFI questionnaire before subjecting them to threshold testing. In order to prevent visual cues from prompting responses, each participant was blindfolded before starting the chemosensory testing procedure. Stimuli used for the tests include Carbon Dioxide for trigeminal, Phenyl Ethyl Alcohol for the olfactory, Citric Acid and Salt (NaCl) for the sour and salty tastes of the gustatory, and a small, continuous electrical signal for the pain perception.

After all the number crunching of the data collected from a total of 126 healthy subjects (41 men, and 85 women), and the necessary corrections the researchers found out that there is a small, but significant positive correlation between agreeableness (people perceived as kind, sympathetic, cooperative, warm, and considerate (Burger, 2011)), and orzo detection sensitivity. This means that although the effect is small, people who score higher in that dimension or the personality test tend to have more sensitive noses as compared to people who scored low in agreeableness. In addition to this, the same trend is found in neuroticism (characterised by anxiety, fear, moodiness, worry, envy, frustration, jealousy, and loneliness (Burger, 2011) and trigeminal chemosensory detection sensitivity. Conversely, there are no significant patterns found between extraversion, and openness to any of the perception taste used in the experiment.

Image Sources:

NEO-FFI

- http://www.psihoterapeutul.ro/wp-content/gallery/neo-ffi/neoffi2.jpg

5 Dimensions

- http://2012books.lardbucket.org/books/psychology-research-methods-core-skills-and-concepts/section_09/ef2ea72504412c1ca95aadcd08ca6c14.jpg

References:

Burger, J. M. (2011). Personality (8th Edition ed.). Belmont, California, United States of America: Cengage Learning.

Croy, I., Springborn, M., Lotsch, J., Johnston, A. N., & Hummel, T. (2011). Agreeable Smellers and Sensitive Neurotics - Correlations among Personality Traits and Sensory Threshold. (H. Matsunami, Ed.) PLoS ONE , 6 (4).

Purves, D., Augustine, G., Fitzpatrick, D., Hall, W., La Mantia, A.-S., & White, L. (2012). Neuroscience (5th Edition ed.). Sunderland, MA, United States of America: Sinauer Associates, Inc.

Tactile Illusion: An Explanation

Before anything else, check out this BuzzFeed video about how to trick your sense of touch:

Coolbeans, yeah? But the question is, how is it possible that we’re able to feel all these illusions even though we know we’re being tricked? Here are the scientific and psychological answers to those questions.

1.     1. Sound and Touch – the first illusion

In this first trick, the guy in the video is writing something on the chalkboard while hearing the scraping of the chalk on the board. Afterwards, he is asked to wear earplugs so he wouldn't hear anything. He reported to have felt like the texture was smoother than before. How is this possible?

This is actually possible due to the connections in our brain. We don’t feel the senses separately, we actually integrate the senses together in our brain. In our auditory cortex in the brain, which is right about here:

There is a belt surrounding the auditory cortex, wherein the integration of the senses of touch and hearing can occur. Hearing something and touching something at the same time is more likely to be associated with one another as well. The integration of senses happens in the brain. (Kayser, et. al, 2005)

However, it seems that the texture of the surface (whether rough or smooth) is an exception (Lederman, 1979). Other studies showed that haptic sense (or touching the object) actually overpowers the auditory senses in other characteristics but surface texture is more affected by auditory than haptic cues (Lederman, et. al, 2002)

2.     Imaginary String – Suggestion and Sense of Touch

Amazingly enough, this one can be explained with fatigue. The muscles on your fingers aren’t meant to stay that way, so once you start relaxing your finger muscles, they come back together. However, suggestion and sense of touch do come hand in hand.

In one research, it was found that a request made by the “toucher” to the “touchee” was more likely to be granted than if the “touchee” wasn’t being touched. This was in a restaurant setting, wherein the touchers were the customer service crew and the touches were the customers. The customers gave higher ratings to the service crew and gave bigger tips if they were touched than if they weren’t. The service crew would lightly touch the customer’s forearm. Unfortunately, it’s still unknown as to why this is the case today. All that’s known is that there’s a correlation between suggestion and touch in consumer behaviour research (Gueguen, Jacob, & Boulbry, 2007)

3.     Hot and Cold – Thermal Grill Illusion

For this trick, the woman puts her hands in hot and cold and then puts her hands in lukewarm water and describes the feeling as strange and confusing as to what the actual temperature of the warm water would be. Pushed further, it is something called the thermal grill illusion.

The thermal grill illusion is when you switch from hot to cold and cold to hot quickly and your brain gets confused about what sense to feel. Research shows that it’s actually more uncomfortable than feeling normal hot and cold (Bach, et al, 2011).

Why exactly do we feel this way? According to a recent research study which recorded the fMRI of people experiencing the Thermal Grill Illusion, the biggest influence in our brain (aka, the one most active during the experience) is actually the thalamus (Lindstedt, et al, 2011). The thalamus’ job is to regulate the senses and the body.

So why exactly is it important to study the reasoning behind the illusion? Well, there is this certain disorder called the cold allodynia, which makes a person feel like the normal cold is more painful than normal. Research has been conducted on the pain receptors before, but it’s much more data enriching and useful to know which parts of the brain are activated in healthy human beings in order to identify what could be going wrong in people with these disorders and what to prescribe or do with them.

4.     Dead man’s Finger – All in the Brain 

In this illusion, stroking the finger of another person managed to make your finger feel numb. Surprisingly, the answer for this question is more biological than psychological. According to research, it was found that the key to getting the “Numbness Illusion” to your brain is not the visual or the motor senses alone but rather is influenced by the tactile inputs in the primary somatosensory cortex (Dieguez, et al, 2009), thus making it a top down processing rather than a bottom up.

References:

Bach, P., Becker, S., Kleinböhl, D., & Hölzl, R. (2011). The thermal grill illusion and what is painful about it. Neuroscience letters, 505(1), 31-35.

Dieguez, S., Mercier, M. R., Newby, N., & Blanke, O. (2009). Feeling numbness for someone else's finger. Current Biology, 19(24), R1108-R1109.

Guéguen, N., Jacob, C., & Boulbry, G. (2007). The effect of touch on compliance with a restaurant's employee suggestion. International Journal of Hospitality Management, 26(4), 1019-1023.

Kayser, C., Petkov, C. I., Augath, M., & Logothetis, N. K. (2005). Integration of touch and sound in auditory cortex. Neuron, 48(2), 373-384.

Lederman, S. J. (1979). Auditory texture perception. Perception, 8(1), 93-103.

Lederman, S. J., Klatzky, R. L., Morgan, T., & Hamilton, C. (2002). Integrating multimodal information about surface texture via a probe: relative contributions of haptic and touch-produced sound sources. In Haptic Interfaces for Virtual Environment and Teleoperator Systems, 2002. HAPTICS 2002. Proceedings. 10th Symposium on (pp. 97-104). IEEE.

Lindstedt, F., Johansson, B., Martinsen, S., Kosek, E., Fransson, P., & Ingvar, M. (2011). Evidence for thalamic involvement in the thermal grill illusion: an FMRI study.

Ratatouille: That Sounds Sweet!

Whenever I watch Pixar’s Ratatouille, one of the most fascinating scenes was seeing Emile consume a grape and a piece of cheese while Remy describes the experience. While Remy describes a “creamy, salty, sweet” and “oaky nuttiness”, what I think is a low bass guitar plays softly in the background. As he describes “smooth, crisp, slight tang on the finish”, sweet percussion instruments create an ethereal sound. When Emile eats the two together, an explosion of color and an amalgam of sound occurs. While it may seem like the director Brad Bird used creative license here, he actually wasn’t off the mark. Contrary to popular belief, taste is a multimodal experience. This means that we recruit all 5 senses- hearing, taste, touch, smell, and sight- when we savor our food. In fact, the color (for example, red) can enhance the sweetness of let’s say, strawberries. It’s easy to see how vision or smell might influence taste, but what does hearing have to do with it?

Researchers have already established that we tend to use the same adjectives to describe music and our taste experience (Knöferle and Spence, 2012; as cited by Kontukoski, et al., 2015). For example, “sweet” ,”dry”, “light”, “soft”, and “crisp” are all words I’d use to describe an introductory Disney movie song and a good bag of potato chips. People also take these associations a step further. When musicians were asked to improvise musical theme from basic taste words like “sweet”, “salty”, “bitter”, and “sour”, certain words corresponded to certain musical patterns (Mesz, Trevisan, & Sigman, 2011, as cited by Kontukoski, et al., 2015). Take a look at the song Edeilwess, as sung by Captain Georg Von Trapp (Theodore Bikel) in Rodger and Hammerstein’s Sound of Music.

The flow of the song is consistent, slow, and soft. This was similar to the patterns created by the taste word “sweet”. On the other hand, take a look at the song Your Fault from Into the Woods (2014).

It seems erratic or dissonant as the different characters chirp in with often high-pitched voices. These sort of musical patterns were improvised under the “sour” category. Lastly, “bitter” improvisations were both low-pitched and legato, much like the Gregorian chanting seen at the beginning of The Hunchback of Notre Dame’s Hellfire.

People also link music to other words related to the basic tastes. For example, in Kontukoski, et al.’s (2015) study, people often used the words like “chocolate”, “tasty”, “dessert”, “velvety”, and “creamy” to describe a “sweet” musical piece- all words I’d associate with having a great experience savoring a decadent piece of chocolate cake. On the other hand, people used more “unpleasant” taste sensations when describing “sour” music, like “hard”, “pungent”, “strong”, and “burning”, among others.

Listening to certain kinds of music not only influence associations, but how we choose to act.   Kontukoski, et al. (2015) also asked their participants to mix a drink after listening to a piece of music. When people listened to “sweet” music, their drink had higher sugar content (including honey, mango juice, and pineapple juice). The reverse was found after listening to “sour” music; the drink had more sour ingredients with higher acidity (lemon and pineapple juice).

Dr. Frankenstein was probably listening to some weird music when he made his monster...

While all these things seem to occur in the vacuum of an experiment, these effects are also evident in a world where Top 40 songs are constantly blaring on as we eat at fast food joints. Music may seem like background noise as you concentrate on that juicy piece of chicken in front of you, but it may play a much more important role than many realize. For example, one study (Wang  & Spence, 2015) was set up in a wine tasting event with live classical music. When a high-pitched and fast Debussy piece was played, the wine was given significantly high acidity and low fruitiness ratings. However, the slower Rachmaninoff piece was given the opposite (low acidity, high fruitiness). This was true whether a person was given red wine, which tends to be sweeter, or white wine, which was made to be more sour and citrusy. Looking back on word-associations, this actually makes sense (you’ll have your explanation later, but I don’t want to spoil it for you …try figuring it out). 

They also tried seeing how music influences our experience of an all-time favorite of mine, chocolate (Carvalho, et al., 2015). This time, they used a Brazilian song- a song that wasn’t deliberately manipulated to modulate taste like in previous experiments. They found out that when the participants were told that the chef used the music as his source of inspiration for creating the chocolate, they significantly liked the chocolate more as compared to other conditions wherein they were not told as such. In fact, they enjoyed it so much that they were also the most willing to pay for it! It didn’t matter that the participants didn’t know who the chef was or were unfamiliar with the music, they nevertheless still enjoyed it. This honestly seems like an interesting marketing strategy. Could this be the end of an era where famous

Inspired by Cool for the Summer by Demi Lovato

people create fragrances with their name slapped on it, and the start of a new craze where chefs create mints dedicated to 5 Seconds of Summer’s new album? While it is an interesting proposal, the problem here is that by simply creating an air of likeability for the chocolate (“Wow! The chef handcrafted this chocolate because he was inspired by the music? This is special!”), this may have contributed to the participants’ tasting experience.

But what could be the reason behind these associations and preferences? One fascinating explanation is through the cognitive priming theory. Let us use the aforementioned Debussy piece to argue this case. Because we derive symbolic meaning (a fast pace and high-pitch is related to “sourness”) from the music we hear, we also activate information related to these terms (“sourness” strongly relates to “acidity”). When this happens, it becomes easier to access these ideas when we think about something.  So these associations ("Man, this drink sure has high acidity!") are what we retrieve as we taste and evaluate the wine.

I must end this post with a small word of caution: as with many crossmodal studies, we have yet to truly establish how the relationship between music and taste perception works. But while we can’t definitely say that food tastes better when accompanied by the right music (thanks to priming), it definitely wouldn’t hurt to try eating some French food while listening to the Ratatouille soundtrack.

Carvalho, F. R., Van Ee, R., Rychtarikova, M., Touhafi, A., Steenhaut, K., Persoone, D., & Spence, C. (2015). Using sound-taste correspondences to enhance the subjective value of tasting experiences. Frontiers in psychology,6.

Knöferle, K. and Spence, C. (2012), “Crossmodal correspondences between sounds and tastes”, Psychonomic Bulletin & Review, Vol. 19, pp. 992-1006

Kontukoski, M., Luomala, H., Mesz, B., Sigman, M., Trevisan, M., Rotola-Pukkila, M., & Hopia, A. I. (2015). Sweet and sour: music and taste associations. Nutrition & Food Science, 45(3), 357-376.

Mesz, B., Trevisan, M.A. and Sigman, M. (2011), “Taste of music”, Perception, Vol. 40 No. 2, pp.209-219.

Wang, Q. J., & Spence, C. (2015). Assessing the Effect of Musical Congruency on Wine Tasting in a Live Performance Setting. i-Perception, 6(3), 2041669515593027.