Explain – Give a detailed account including reasons or causes Explain the Functions of Hormones in Human Behavior - Biological Level of Analysis Explain – Give a detailed account including reasons or causes

Explain the Functions of Hormones in Human Behavior The Function of hormones: Similar to neurotransmitters because they are both chemical messengers, but they differ in a number of ways: Hormones are released into the bloodstream and travel with blood to reach their destination Hormones can regulate long-term ongoing processes such as growth, metabolism, digestion or reproduction (nervous system regulates rapid processes like movement, emotion, decisions, etc.) Lack of voluntary control over hormonal regulation (you might be able to control your emotions (nervous system), but not your growth (hormonal) The nervous system and endocrine system are interdependent – they interact and can influence each other. Some chemicals can be both hormones and neurotransmitters (Adrenaline)

Explain the Functions of Hormones in Human Behavior Function of hormones Hormones are released by endocrine glands Adrenal glands, hypothalamus, pineal gland, pituitary gland, thyroid, parathyroid, thymus, pancreas, testes, and ovaries Hormones can only influence cells that have receptors for this particular hormone Called target cells Hormones do not influence behavior directly, instead, they change the probability that a certain behavior will occur in response to a certain environmental stimulus Ex. Buying ice-cream on a hot day (hot weather doesn’t make you buy ice-cream, it just increases the probability that you will)

Explain the Functions of Hormones in Human Behavior Some of the most well known hormones are: Adrenaline, cortisol, oxytocin, insulin, testosterone, and estrogen We will be focusing on OXYTOCIN

Explain the Functions of Hormones in Human Behavior Oxytocin Produced in the hypothalamus and released into the blood by the pituitary gland Plays a role in sexual reproduction, childbirth and social bonding referred to as the “love hormone”, ”the bonding hormone”, and “the cuddle hormone”. Ex. Released from stimulation of nipples during breastfeeding and this helps to establish a stronger bond between mother & child. Also released with every kiss or hug. https://www.youtube.com/watch?v=rFAdlU2ETjU

The role of oxytocin in interpersonal trust Kosfeld et al (2005) Aim: to determine if oxytocin increases trust in humans Methods: Participants were 128 healthy male students (mean age: 22 years) Subjects were randomly allocated into either the oxytocin group or placebo group Substances were administered via a nasal spray For the purposes of the experiment, the researchers designed a trust game with real monetary stakes. In this game subjects were paired anonymously and played the role of either an investor or a trustee. Each round of the game (each with a new partner) consists of three steps Step 1: the experimenter gives both the investor and the trustee an endowment of 12 monetary units Step 2: the investor needs to decide how much of that to send to the trustee (there are four options: 0, 4, 8, 12). The experimenter triples whatever is sent to the trustee. Step 3: the trustee decides how much of the now available money to send back to the investor. The idea is that if I (the investor) completely trust you (the trustee), I will send you all 12 monetary units, it will turn into 36, and I trust that you will send me back at least 18 and maybe more. Can I trust you though? We only interact once during this experiment, so you have a temptation of keeping the whole sum with you. In order to trust you, I need to overcome aversion towards this risk. Participants played the game four times in the same role, each time paired randomly with a new partner. At the end, the total earned monetary units were exchanged for real money

Explain the Functions of Hormones in Human Behavior Results of Kosfeld et al (2005) Results of the experiment showed that the level of trust in those participants who received a dose of oxytocin was higher than in the control group. The median transfer of investors was 10 in the oxytocin group and 8 in the control group 45% of subjects in the oxytocin group showed the maximum trust level (12 monetary units), whereas only 21% in the placebo group showed the maximum trust level. The researchers suggested two alternative explanations for this finding: Oxytocin reduced risk aversion in general Oxytocin increases people’s trust in other humans Researchers then followed-up the study with another group of people but this time they were playing the game against a computer software. Results were very similar, but with the software, the median transfer was eight monetary units in both conditions. The researchers concluded that oxytocin specifically affects trust in interpersonal interactions.

The role of oxytocin in fidelity Scheele et al (2012) Aim: to determine if oxytocin modulates social distance between men and women Methods: Studied 86 heterosexual men Some were single and others were in a stable monogamous relationship Using a double-blind independent measures design, a researcher administered either oxytocin or a placebo intra-nasally Subject participated in two independent tasks: 1st task – “stop-distance paradigm” Subjects were positioned at one end of the room while an attractive female experimenter was positioned on the other side of the room The subject was then required to move slowly towards the female experimenter and stop at a distance that made him feel slightly uncomfortable Care was taken to assure that the experimenter maintained the same appearance over all trials 2nd task – “approach/avoidance task” Subjects viewed a series of pictures on a screen with their head positioned on a chin rest at the viewing distance of 50 cm. Pictures were flashed for two seconds each There were four types of pictures shown in random order Positive social (attractive women), positive non-social (beautiful landscapes), negative social (mutilations), and negative non-social (dirt). All participants had a joystick, and if they liked a pic, they were instructed to pull the joystick, which resulted in an increase in the picture’s size Conversely, if they didn’t like what they saw, they pushed the joystick and this reduced the picture’s size

The role of oxytocin in fidelity Scheele et al (2012) Results: Results of the first task showed that oxytocin stimulated men in a monogamous relationship, but not single ones, to keep greater distance between themselves and an attractive woman It was concluded that oxytocin caused men in a relationship to “stay away” from an attractive woman who was not his partner Results of the second task showed that the only group of pictures affected by oxytocin and relationship status was the positive social group (pictures f attractive women) Specifically, participants who received oxytocin had slower reaction time (pulled the joystick more reluctantly) in response to these picture, but only if they were in a relationship. It was concluded that oxytocin selectively inhibits approach to certain stimuli – attractive women – in men who are in a stable relationship, but not in single men. From the results of these trials it is seen that by selectively influencing men in a relationship to keep greater distance from attractive women they do not know, oxytocin may promote fidelity.