Author: Evangelia Diplas

This year, I have been working with Dr. Rodman and her graduate student to design a study examining how one’s chronotype interacts with the ambient lighting environment (warm, dim light light versus cool, bright light) to affect how people perceive facial expressions of varying intensities.  

Recall that chronotype refers to one’s natural inclination to sleep and wake at certain times in the 24 hour cycle.  Morning-oriented individuals prefer to sleep earlier and wake up earlier, while evening-oriented individuals prefer to sleep later and wake up later.  Blue light has been shown to increase alertness, and past studies have shown that evening-oriented individuals are at a greater risk for developing mood disorders such as depression. The lab hypothesizes that this may due to evening-oriented individuals’ greater exposure to bright (blue) light, as they may be perceiving negative (or neutral) facial expressions as more negative, due to increased alertness.

About two weeks ago, a graduate student and I started collecting data.  Prior to bringing participants into the lab, though, we had to prepare the experiment room.  The room is quite small, and we hung a curtain to partition it, so that when the experimenter opens the door the outside light does not enter the room and confound our results. Additionally, we set up two lamps with dim and bright settings and randomly assigned participants to each treatment group.

I am responsible for running six participants a week.  After participants sign the form of consent, I give them a packet of questionnaires regarding chronotype, sleep habits, eating habits, creativity, etc.  I then set a timer for 20 minutes, and they fill out the packet inside the experiment room. Participants must remain inside the room for 20 minutes in order to adjust to their prescribed lighting environment before they take the computer task.  (If a participant finishes early, I am instructed to tell them to continue checking over their answers and stay inside the room until the 20 minutes has elapsed.) Then, subjects must complete a computer task, in which faces are flashed across the screen for short, varied amounts of time.  The faces exhibit different emotions (happy, sad, fearful, surprised, angry) and are mixed with varying levels of the original neutral face. I instruct participants to rate what expression they think they see, and how confident they are in their rating, from a scale of 1-4.  Lastly, I debrief subjects on the true purpose of the study, as we had originally told participants that we were researching how personal preferences affect our perception of emotions. For the rest of the semester, I will continue to run participants and collect data.

In my previous post, I discussed the senior thesis of a former researcher in Dr. Rodman’s Lab, Eli Recht.  His work on “Chronotype and Facial Affect Processing” is directly related to what my lab is currently working on.  Our next experiment will essentially address Eli’s future directions as well as our own evolving research questions.

How does Eli’s research relate to the lab’s current work?

The lab’s main focus is still on the effect of chronotype (whether or not a person is more morning or evening-oriented) on facial affect processing and mood disorders.   However, we are planning to alter quite a few aspects of the experimental design this time around.  For instance, the lab discovered a time-of-day effect when analyzing the data from Eli’s experiment. Subjects tested in the evening consistently rated expressions more intensely than those tested in the morning, and the effect was found regardless of chronotype. Consequently, we are planning to test our subjects exclusively in the evening (rather than at different points in the day) because we are more likely to find an effect.  Moreover, we plan to test subjects under different lighting environments and observe the effects on mood, attention, and circadian rhythms.  Additionally, whereas Eli’s study focused on subjects rating the emotional intensity of faces, we are planning to focus on emotional identification. We are also planning to flash faces onto the computer screen for short durations of time and ask subjects for confidence ratings.  Perhaps these confidence ratings will give us new insights regarding which types of people are more confident about their assessments of emotional intensity.  We can ask questions such as: Will there be a chronotype effect? Will the presence of a mood disorder (such as depression) play a role in how confidently people identify emotions?  Other than a few more changes, the new experiment will be conducted in a similar manner to Eli’s, using many of the same questionnaires.

What am I currently working on?

In addition to helping my lab develop the future experiments, I have been reading scientific papers about chronotype and the Three Factor Eating Questionnaire (TFEQ).  The TFEQ is a 51 item questionnaire developed by Stunkard and Messick (1985) to examine three factors of restrained eating, which is intentionally restricting the amount of food consumed to control weight. The three factors are (1) cognitive restraint, (2) disinhibition, and (3) perceived hunger.  Cognitive restraint is further divided into rigid and flexible control.  Rigid control is an “all-or-nothing approach,” whereas flexible control is “a more graduated approach to eating and dieting” and is thus considered healthier (Schubert and Randler).  In their 2008 study entitled Association between chronotype and the constructs of the Three-Factor-Eating-Questionnaire, researchers Eva Schubert and Christoph Randler discovered a few interesting relationships.  They observed a positive association between morningness and cognitive restraint, as well as between morningness and flexible control. There was also a negative association between morningness and disinhibition, as well as morningness and perceived hunger. This all seems to support the claim that “morning people” tend to lead healthier lifestyles.

My P.I also recently had me read a paper entitled The Three-Factor Eating Questionnaire-R18 Is Able to Distinguish among Different Eating Patterns in a General Population by Blandine de Lauzon et al. (2004).  This paper discusses the validity of the shorter version of the TFEQ called the R-18; it has 18 items instead of 51.  Its sub-scales include (1) cognitive restraint (CR), (2) uncontrolled eating (UE), and (3) emotional eating.  Despite the fact that we only used the TFEQ-18 as a filler survey in Eli’s study, it may nonetheless provide us with important information.  I am currently working alongside a graduate student in my lab to analyze the data.  We are still in the beginning stages of this analysis, but we are curious to see if we will find similar associations between chronotype and eating behavior in our own data.  Moreover, we could look to see if there are any correlations with negative or positive facial expressions.

Lastly, I am personally interested in seeing whether or not there is a relationship between chronotype and creativity.  My hypothesis is that evening-oriented individuals will tend to be more creative.  (My rationale is based on the idea that there have been many instances of famous artists and composers furiously working on their projects throughout the night, in fits of inspiration. Perhaps this also has to do with overlaps with mood disorders.) Most creativity tests involve tasks of some sort (with physical objects or drawing pictures), but in order to include it as a part of the lab’s next study, I must devise an alternative method. I am in the process of developing this filler questionnaire that we can use in our next project to collect some pilot data. Additionally, I am still deciding whether I would like to ask questions about the Big Five personality characteristics, or if I want to focus on breaking down creativity into facets including musical, artistic, and literary creativity, among others.

Chronotype and Facial Affect Processing: An Assessment Among the College Population

By Eli B. Recht

Paper Overview:

My assignment for my first week in Dr. Rodman’s lab was to read the Senior Thesis of one of her former researchers, Eli Recht.  

Eli starts out by mentioning that past research indicates that evening-oriented individuals have a predisposition for developing mood disorders, which impairs social functioning.  His particular research looks at the impact of chronotype (individual circadian rhythms) and temporal (time of day) preference on social cognition, particularly facial processing.  In other words, he wanted to see whether or not eveningness is related to social cognition. Eli’s paper includes literature reviews on the topics of chronotype and facial affect processing, which then allowed him to form his own hypotheses. Personally, the literature reviews were beneficial to read, as I am new to the topic.

Literature Review of Chronotype:

First, Eli gives the reader some background information on circadian rhythms. Circadian rhythms are 24-hour internal rhythms influenced by zeitgebers (external cues from our environment) such as light.  Humans are diurnal, meaning that we are active during periods of light and rest during periods of dark. The hypothalamus’ suprachiasmatic nucleus (SCN) synchronizes many functions (including daily rhythms of wakefulness and sleep, hormone secretion, body temperature, performance, endocrine regulation, metabolic activity, sensory integration, alertness, heart rate, and gene expression) when it receives light signals through the retina.  Circadian malleability refers to the flexibility of our rhythms to adapt to a changing environment, which is why we can alter our circadian rhythms with artificial light.  Our circadian rhythms can also be altered by non-photic zeitgebers, including body temperature, attention, memory, sensory integration, locomotor activity and exercise, exogenous melatonin, food intake, drugs, stress, emotion, and social interaction.  

Moreover, Eli discusses the differences between owls and larks. Owls are those who prefer to be active in the evening, whereas larks prefer to be active in the morning and have earlier times of peak alertness and food intake, and higher daytime core body temperatures.  Larks also have more regular sleep patterns, as well as less disrupted sleep and sleep deprivation, compared to owls. Consequently, though, larks are less flexible in terms of shifting their sleep schedules.  Additionally, owls and larks differ in their personality traits and moods; larks are cooperative, empathetic, motivated, whereas owls tend to be more pessimistic and show symptoms of major depression.

Interestingly, Eli mentions that eveningness is actually a genetic predisposition (vulnerability) for developing depression. In fact, light can be used as a treatment to improve mood for both owls and depressed people.  Eli also discusses the influence of sociality on owls and depressed people.  Staying up late to socialize with friends may actually cause depression by delaying one’s biological clock, leading to dysfunction of the SCN (which is connected to the limbic system and thus, emotions).

Literature Review of Facial Affect Processing:

Facial affect processing is the system by which we detect and interpret facial expressions and is thus critical to social competence. Eli mentions various brain structures involved in this process, including the fusiform face area and orbitofrontal cortex, superior temporal sulcus, and the amygdala.  People with disruptions in sleep, attention, and mood actually perceive things differently, and the same goes for depressed patients, who perceive expressions as more negative.  Also, research shows that people perform better on tasks during their preferred times of activity (relating back to owls and larks).

Hypotheses Generated from Literature Reviews:

1. Evening types will perceive emotional expressions with less emotional intensity than morning or intermediate types, particularly at the low intensity range of expressiveness.
2. Participants tested at their preferred times of activity will perceive facial expressions with more emotional intensity than participants tested at their non-preferred times of activity, particularly at the low intensity range of expressiveness.

Method:

This research was conducted on Emory University students ages 18-24. A Morningness-Eveningness Questionnaire (MEQ) was distributed to the participants to determine chronotype.  Based on the results of the MEQ, students were then placed into two groups, preferred and nonpreferred, referring to the time of day that they were being tested. For instance, an evening-oriented individual being tested in the morning would be placed in the nonpreferred group. The subjects were shown four facial expressions (anger, happiness, sadness, and surprise), each with 10 gradients in emotional intensity.  These expressions were then rated on a 9 point intensity scale, via a computer task.

Conclusions:

There was no significant difference in the average intensity ratings of the four facial expressions between chronotype groups or preferred or nonpreferred time groups; thus, his original hypotheses were not supported.  Eli’s, his experiment was still informative to the lab! He conducted an exploratory data analysis and found a time of day effect.  (An EDA is basically when statisticians see what the data can tell them beyond the original hypotheses in order to form new hypotheses and experiments.) Essentially, subjects would rate the intensity of facial expressions higher at the higher ranges of intensity during the evening.  (This means that, for example, at night, you are more likely to perceive someone’s expression as even more intense than usual.)

Questions/ Future Directions:  

Based on this study, perhaps we could look further into the time of day aspect. Also, I am curious to see if we could expand this research to other age groups.