Master thesis
MANIPULATING EMOTIONAL AROUSAL
USING EXTERNAL SECONDARY STIMULI
August 16th 2019
Jacob Brok-Jørgensen
Engineering Psychology, Group 1089a
Electronic Systems, Aalborg University
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Manipulating Emotional Arousal with External Stimuli: Study on Background Lighting, Study notes of Experimental Design
The possibility of using subtle background stimuli, specifically lighting, to influence a person's level of physiological arousal. The study, conducted as a master's thesis, used Galvanic Skin Response sensors to measure physiological arousal levels. However, the results showed no significant effect of lighting on participants' physiological arousal or performance. The document also discusses various theories explaining the underlying processes of emotions and the role of physiological arousal in emotion production.
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Master thesis
MANIPULATING EMOTIONAL AROUSAL
USING EXTERNAL SECONDARY STIMULI
August 16 th^2019
Jacob Brok-Jørgensen
Engineering Psychology, Group 1089a
Electronic Systems, Aalborg University
[email protected]
Contents
- 1 Introduction
- 1.1 Physiological factors of emotion
- 1.2 Theories of emotion
- James-Lang
- Cannon-Bard
- Two-Factor Theory
- Appraisal Theory
- 1.3 Research Question
- 2 Method
- 2.1 Background Stimuli
- 2.2 Main Stimuli
- 2.3 Measurement
- 2.4 Experimental design
- Setup
- Procedure
- Participants
- 3 Results
- 4 Analysis
- 5 Discussion
- 5.1 Results
- 5.2 The experiment
- 5.3 Unintended factors
- 6 Conclusion
- Bibliography
- Appendices
- A Timeseries data
- B Electronic Appendix
- C Electronic Appendix
- D Electronic Appendix
- E Electronic Appendix
Introduction
Any stimuli has the potential to change our emotional state, almost everyone has experienced this when listning to music, watching a movie, or reading a book. Stimuli outside of our selves have a huge capacity to influence how we feel. Our understanding of the way emotional changes take place has changed over time, some theories assert that emotions are less discrete categories but rather a product of physiological and cognitive processes, responding to a stimuli. This idea that emotions are essentially a product of several different factors is teased all the way back in Wundt and Judd’s Outlines of psychology (Pages 358-368). Wundt identified three main factors, Quality, Intensity and Form of occurrence, as the building blocks of any emotion, and used these to describe the differences between the more well- know categorical emotions(fear, anger, joy, exitment, etc.). Joy and rage for instance exhibit widely different affective qualities but, when it comes to intensity and form of occurrence, manifest in quite similar fashion. Wundt also details that there is an inherent linguistic limitation when trying to describe emotion. This is exemplified by the fact that anger, while remaining clearly identifiable as such can have a variety of forms of occurrence, just as surprise can have both a pleasant and unpleasant quality.
This idea of a multidimensional model describing emotion has changed over time, with Russell (1980) proposing a circumplex model, shown in Figure 1.1 , based on multiple analysis methods like principal component analysis and multidimensional scaling, resulting in a model with two main dimensions interpreted as valence and arousal. These describe the pleasantness and energy of an emotion, for instance terror is very unpleasant and has high energy, while contentment is pleasant and has low energy.
Group 1089a 1. Introduction
Figure 1.1. X-axis shows the Valence rating of an emotion. The Y-axis shows the arousal. On the graph several categorical emotions are represented, according to their presumed levels of valence and arousal. Source: Russell, 1980
While these models are useful for describing emotions, they do little to explain the underlying processes which make up the emotions we feel, for this purpose several theories have been developed. In order to understand and discuss these theories the terminology used in describing them needs to be made explicit.
1.1 Physiological factors of emotion
When a person is exposed to an emotional stimuli, it will often change the persons physiological arousal in one way or another Kreibig, 2010. Physiological arousal refers to an activation in the sympathetic division of the Autonomic Nervous System(ANS). The sympathetic division includes various physiological systems shown on Figure 1. Physiological arousal is more commonly referred to as the fight or flight response. The sympathetic division is only one half of the ANS with the parasympathetic division making up the other half. The parasympathetic division controls the processes relate to resting, digesting and replenishing, as shown on Figure 1.2. These parasympathetic processes are essential to maintaining homeostasis, while prolonged activation of the sympathetic division prevents the parasympathetic division from being active, leading to a depletion of essential resources and pushing the person toward exhaustion and eventually chronic stress.
Group 1089a 1. Introduction
James-Lang
According to the James-Lang theory, the physiological arousal respons contains all the information needed to produce an emotion and no cognition/consideration of the initiating event is necessary for a person to experience and emotion, the sequence of the theory is shown in Figure 1.3.
Figure 1.3. Shows the basic flow of an emotion response according to the James-Lang Theory of emotion, inspired by KhanAcademy (2019). An event leads to physiological arousal, which is then interpreted, leading to an emotion.
In order to show this an experiment was conducted by Ax, A. F. (1953). The physiological differentiation between fear and anger in humans. Psychosomatic medicine, 15 (5), 433– in which participants were either angered or frightened, and a clear difference was pressent in the physiological response despite the experience of either experiment was quite similar in many respects.
Cannon-Bard
This theory is a response to certain inadequacies of the James-Lang theory. Through Animal experiments Cannon (1927) has show that severing connections between the brain and various parts of the sympathetic ANS resulted in no change to the animals ability to show anger and rage in a behavioural manner. This despite not showing any of the usual physiological symptoms of anger and rage.
Figure 1.4. Shows the basic flow of an emotion response according to the Cannon-Bard Theory of emotion, inspired by KhanAcademy (2019). An event leads to physiological arousal and an emotion simultaneously.
An event leads to a simultaneous physiological response and emotional experience, as such the emotional context of the experience is in no way influenced by any physiological changes.
Two-Factor Theory
Schachter and Singer (1962) created the Two-Factor Theory to account for evidence supporting both the James-Lang and Cannon-Bard theory of emotion. By inducing a physiological arousal response through injections of epinephrin, and using social stimuli to provoke anger and elation in subjects, Schachter was able to show that when a person is not able to explain physiological arousal these feed into what ever emotion an event
1.3. Research Question Aalborg University
might elicit. However, when an explanation for the physiological symptoms is pressent the emotional response is unaffected.
Figure 1.5. Shows the basic flow of an emotion response according to the Two-Factor Theory of emotion, inspired by KhanAcademy (2019). An event leads to physiological arousal, which is then interpreted in the context of the event, leading to an emotion.
An event leads to physiological arousal, this arousal response is then interpreted in the context of the event, taking into account past experiences, prior mental state and the larger context of the event. Only after processing all elements can a person actually feel the emotion.
Appraisal Theory
The goals of Appraisal Theory were to give a more comprehensive explanation of the processes that produce emotion, in order to account for several unaddressed weaknesses with alternative theories.
Figure 1.6. Shows the basic flow of an emotion response according to the Two-Factor Theory of emotion, inspired by KhanAcademy (2019). An event is appraised, and labeled, based on this label physiological arousal and an emotion is felt.
The event is appraised and receives a rudimentary emotional label, based on this label a physiological arousal response is induced and an emotion is felt. Scherer, Schorr, and Johnstone (2001) lists several weaknesses with alternative theories.
- Many theories rely heavily on dimensional models of emotion which do not account for evidence supporting the idea of distinct emotions. 2) A single event can evoke different emotions in different people, 3) just like different events can evoke the same emotion. 4) Emotions are more often than not appropriate to a given event like the calming nature of sadness following unavoidable tragedy, where the very active nature of anger or rage would have been a wast of energy.
1.3 Research Question
While the scientific community has yet to agree on a single definitive theory or model to describe emotion, it seems clear that, among other things, a persons physiological arousal is central and of great importance to the process. Prolonged exposure to stimuli, or stressors, can lead to chronic stress, this in turn can have detrimental effects on a persons ability to solve problems, and can elevate the risk of acquiring a wide range of ailments, ranging from depressions to cancer.
Method
In this chapter the methods and tools used to answer the research question are presented and discussed. This includes background and main stimuli, and a method for measuring physiological arousal. Finally the experimental setup, procedure and considerations regarding participants are also presented.
2.1 Background Stimuli
The first element that needs to be decided in order to examine the research question is a background stimuli. There are several considerations which need to be taken into account for this choice. As stated previously the goal is to examine the viability of a tool to help manage stress. As such the background stimuli needs to be realistically implementable in a persons daily life. This means that it must be subtile enough that it dosen’t distract too much from other activities, eliminating any stimuli that requires action or conscious response on the part of the subject. It also limits possible stimuli to systems that can be implemented in locations where a person might normally be exposed to stressors like at home or in the workplace. Alternatively, a stimuli that a person can carry with them at all times would also work. The background stimuli also needs to be proven to actually influence the physiological arousal of a person. Several potential stimuli have been shown to influence a persons physiological arousal, for instance thermal stimuli (Salminen et al., 2011), color and temperature of lighting (Smolders & de Kort, 2017)(Kang, Youn, & Yoon, 2019).
For the purposes of this thesis color lighting is chosen as the background stimuli based on the criteria listed above. For the implementation, a Philips Hue Bridge v1.0 with three E White and Color Ambiance Lightbulbs are used. The color and intensity of the lighting is controlled using the companion smartphone application. Philips Hue v1.0 comes with several standard lighting ’Scenes’ like Arctic Aurora and Tropical Twilight which utilise several different colors and brightnesses for the three lightbulbs. Also included are some more subdued ’Scenes’ like Bright or Energize which feature a single color and brightness for all three lightbulbs. The lighting modes Energize, Bright and Concentrate are chosen as these represent a cold, warm and neutral temperature of lighting respectively. The illuminance of each of the three settings is measured using a Panlux Electronic 2 lux-meter at the approximate location of the subjects head facing straight up, see ??
Group 1089a 2. Method
Figure 2.1. Panlux Electronic 2 lux-meter at the approximate location of the subjects head facing straight up
- The Energize mode feature a slight blue hue, the illuminance is measured at 1750 lx.
- The Bright mode features a slight orange hue, the illuminance is measured at 1500 lx.
- The Concentrate mode features a white hue, the illuminance is measured at 1900 lx.
2.2 Main Stimuli
For the main stimuli there is again a list of requirements that needs to be met. The stimuli needs to be proven to produce a physiological arousal response, simulating the stress of a demanding task in a work context or similar. The stimuli should feature a varying level of stimulation over time, to represent several levels of current stress, and to maybe imitate an actual stress response somewhat. Finally the stimuli should be something that a person can re-experience several times. every person is different, and the way they respond to a stressor will vary from person to person. for this reason it is preferred to compare a arousal responses within subject.
A solution that meets these requirements is the game Tetris. The game features a fairly predictable gameplay loop of building up blocks, making the game more and more difficult to manage, while occasionally clearing lines of blocks, in turn making the game easier to manage. The initial base level of challenge for the game can be adjusted before starting the game and will slowly increase as the game progresses constituting a more permanent and constant rise in the level of difficulty. For illustrative purposes Figure 2.2 depicts a fictive game of Tetris in terms of challenge level over time as the player occasionally clears rows and the speed of the game slowly rises.
Group 1089a 2. Method
For this experiment the best suited solution is using galvanic skin response(GSR) electrodes to measure skin conductivity, and use that as an estimate of physiological arousal. In praxis that means using a Shimmer GSR+ with two reusable snap electrodes for the making the actual measurements, combined with the ConsensysBasic software used for logging and exporting the GSR data. For the best results Shimmer (2018) recommends attaching the electrodes to the index- and middle-finger, on the palmar surface of the finger. However, through pilot tests it was found that the reusable velcro straps which are used to attach the electrodes tended to rub against each other causing noise in the GSR data. To avoid this the electrodes were placed on the palmar surfaces of the index- and ring-finger. This way the velcro straps can never rub against each other on accident.
2.4 Experimental design
Setup
The subject sits in a chair in-front of a monitor, mouse and keyboard. The shimmer GSR+ is docked next to the monitor and equipped with two electrodes with reusable velcro mounting straps. The monitor, mouse, keyboard and shimmer dock is connected to a laptop placed next to the monitor, of which the entire experiment is run. The Tetris game is shown on the monitor while the laptop runs the ConsensysBasic software, controlling the Shimmer GSR+. The GSR electrodes are attached to the subjects left hand and they control the game with their right hand exclusively, to avoid any noise or interference on the GSR reading. Gameplay and sound is recorded with the Windows 10 Game Bar screen recording tool, to allow synchronisation between the GSR timeseries data and video of the Tetris gameplay. Three Philips Hue lightbulbs are used, one is placed behind the monitor, the other two are hung from the ceiling behind the subject, one in each corner, about 50 cm from the ceiling and either wall. A sketch of the experimental setup is shown on Figure 2.4.
2.4. Experimental design Aalborg University
Figure 2.4. Sketch of the experimental setup. The three red dots represent the locations of the three Philips Hue Lightbulbs. The blue dot shows the location of the subject and the green dot the location of the facilitator.
The placement of the lightbulbs is shown on Figure 2.5. Figure 2.6 is an image of the entire experimental setup with the subject sitting in the chair on the right and the facilitator in the chair on the right.
Figure 2.5. Left: The placement of the two Philips Hue lightbulbs hanging from the celling. Right: The placement of the lightbulb place behind the monitor.
2.4. Experimental design Aalborg University
Lane and Nadel (2002, pp. 254–260) has shown that there is a difference in the arousal response reported by male and female participants, dependent on the valence of the present emotion. As such, the experiment in this thesis is limited to a single sex, males, as chosen for being over represented and thus easiest available at Aalborg University, Fredrik Bajers Vej 7 where the experiment is conducted and all participants recruited from.