="http://www.w3.org/2000/svg" viewBox="0 0 512 512">

Module 14: Motivation and Physiological Psychology

Module Overview

In Module 13 we examined motivated behavior and how it arises from cognitive processes. In this module we will continue that discussion but look at physiological processes to include biological drives and substance abuse.


Note to WSU Students: The topic of this module overviews what you would learn in PSYCH 372: Biological Basis of Behavior, PSYCH 265: Biopsychological Effects of Alcohol and Other Drugs, PSYCH 230: Human Sexuality, PSYCH 324: Psychology of Gender, and PSYCH 333: Abnormal Psychology at Washington State University.


Module Outline


Module Learning Outcomes

  • Describe how we are motivated to maintain balance.
  • Outline the biological drives of temperature, sleep, hunger, thirst, and sexual behavior.
  • Describe how substances can be used to motivate a desire to feel better.

14.1. Biological Drives: Motivated to Survive


Section Learning Objectives

  • Define and exemplify homeostasis.
  • Define thermoregulation and list types of motivated behavior that affect body temperature.
  • Identify structures and mechanisms that regulate sleep.
  • Contrast hunger and satiety.
  • Describe internal and external signals affecting hunger.
  • Describe the two types of thirst.
  • Describe structures controlling sexual behavior.
  • Outline the sexual response pattern.


14.1.1. Homeostasis

Consider what steps you take to obtain sustenance when hungry, to find water when thirsty, to warm up if cold, or to rest when sleepy. Whatever behaviors are involved, you engage in them almost automatically, and so much so that you likely take for granted how much internal forces affect your daily behavior. Efforts to correct such deficiencies show the work of biological drives (the push of motivation) and attempts to maintain homeostasis or balance within the body. Really, what we are trying to do is maintain an optimal or ideal level for various biological processes such as our body temperature, glucose levels in the blood, blood pressure, or sleep. How so?

Actually, you sort of know how this works already, and especially so if you have a thermostat in your home. You set it to the temperature you want, say 72 degrees. This is the ideal temperature you want and serves as a set point. The thermostat compares the ideal temperature to the actual temperature. If the house is at 69 degrees, then the thermostat will turn on the heat and keep it on until the temperature rises to our set point of 72. At that point, it shuts off. If the house is at 75 degrees, the thermostat initiates action to lower the temperature by turning on the air condition. If actual and ideal are the same, no action is needed. Your body does the same thing. How so? Let’s examine a few drives and how homeostasis is maintained.


14.1.2. Temperature

Since our example dealt with temperature it seems fitting to start here. Maintaining a set core internal temperature is called thermoregulation. For the average person, the core temperature falls between 98 and 100 degrees and going to the extremes can have detrimental effects. If your temperature falls to 95 degrees, you experience hypothermia which can lead to cardiac arrest, brain damage, and potentially death. A rise in temperature to about 107.6 degrees Fahrenheit can cause brain damage or death.

Body temperature can be affected by having a fever, working out, using drugs, digesting food after dinner, or drinking alcohol. Thermoregulation is controlled by the hypothalamus which sends signals out via the peripheral nervous system to your organs, glands, and muscles giving them instructions on how to lower or raise your core temperature. This might include sweating or vasodilation to cool down and vasoconstriction and thermogenesis to heat up.


14.1.3. Sleep

Though we know that sleep is a necessary requirement for all human beings, and is essential for survival, the exact reason(s) is/are not as clear. We spend about one-third of our time sleeping. Several brain structures are involved in the regulation of sleep. First, the hypothalamus contains the suprachiasmatic nucleus (SCN) which is a cluster of cells that receives information about light exposure from the eyes and controls our behavioral rhythms. People with damage to this area sleep erratically because their light-dark cycle and circadian rhythms are not in synch. During all stages of sleep but REM sleep, the thalamus, or sensory relay station, becomes quiet and allows you to tune out the external world. The pineal gland receives signals from the SCN and increases production of the hormone melatonin, which aids in sleeping once the lights are off.

Sleep is regulated by two internal biological mechanisms. First, circadian rhythms affect fluctuations in wakefulness, metabolism, body temperature, and the release of hormones. Specifically, they control the timing of sleep and lead you to feel sleepy at night. Second, sleep-wake homeostasis tracks how much sleep you need and gives the body a reminder to sleep after a certain amount of time. It also regulates sleep intensity.

How much sleep do you need? There is no magic number and in general, it is recommended that adults sleep 7-9 hours a night while babies sleep 16-18 hours a day and school-aged children and teens sleep about 9.5 hours.


For more on sleeping, check out the following information published by the National Institute of Neurological Disorders and Stroke:



14.1.4. Hunger

The biological drive of hunger, or desiring to eat, relates to the end of this motivated behavior once we are full, called satiety. Basically, we eat because there is a deprivation in the amount of glucose in our blood to sustain activity; once we have restored that glucose level to its set point, hunger ends. In other words, we have achieved homeostasis again. The feeling of hunger is not pleasant and results in feeling shaky, lethargic, and possibly being sick to our stomach. We want to do something about this. So how do we know when to eat?

Signals arise from both the stomach (surprising, right?) and the blood, but the stomach plays less of a role then we might realize. We all have experienced hunger pangs or our stomach growling, or the feeling of being full especially after one of our main food holidays (Christmas, Easter, or Thanksgiving). These stomach indicators relate to being very hungry (i.e., being famished) or very full (i.e., stuffed) but that is about it.

What about other possible signals? I mentioned the brain receives information from the blood about levels of glucose, or sugar used by body cells for energy. When our glucose levels are low, we are motivated to eat and restore these levels. The brain also regulates hunger through the action of the hormone ghrelin which increases appetite and leptin which reduces appetite. Other important hormones include GLP-1 which reduces appetite and tells the pancreas to release insulin, CCK which improves digestion by reducing the rate at which food is emptied from the stomach and into the small intestine, PPY which causes satiety by being secreted into the bloodstream by the small intestine and then binding to receptor sites in the brain, and neuropeptide Y which leads to increased consumption of carbohydrates.

Though many areas of the brain are involved in the regulation of hunger, the hypothalamus plays a pivotal role. In terms of knowing when to start eating, the lateral hypothalamus is involved and if stimulated with an electrode, an animal that is in a state of satiation will begin eating. In terms of satiety, the ventromedial hypothalamus tells an animal to stop eating but if destroyed, overeating results. Finally, the paraventricular nucleus is involved in satiety as shown by stimulating it and in overeating if destroyed or damaged. It helps to regulate blood sugar levels.

In addition to these internal signals to eat, several external cues are important too. First, we sometimes eat not because we are hungry, but because it is time to eat. Time of day factors in such that most people eat at noon because our society has been told that we should eat then. Or we might eat on our lunch break at work whether we are hungry or not. Second, social factors play in. We may eat because our friends are doing so and don’t want to be left out. Third, the sight of food, or its smell, may motivate us to eat. Fourth, to deal with life we sometimes engage in comfort eating as a tension reduction strategy, or to deal with stress (See Module 4). Fifth, but more so a cue as to what to eat, culture plays in. Some cultures find our eating of ground beef from cows to be appalling, as much as we find their eating of cats or dogs to be so. Sixth, and as mentioned already, we tend to overeat during certain times of the year such as holidays – Thanksgiving, Christmas, and Easter.

Going back to our discussion of behavioral change from Module 6, if we are trying to get in shape by reducing our caloric intake, we need to take into consideration temptations that could lead us to engage in undesirable or problem behavior. Social eating is one such example of eating when we are not actually hungry.


Note: A discussion of eating disorders is also relevant here but was discussed in Section already. Please look at it again before moving on.


14.1.5. Thirst

There are two kinds of thirst that we can experience. Yes, two. If you eat a salty meal, you experience the first type called intracellular thirst. Excessive salt, such as found in potato chips, causes fluid to be drawn out of our cells and as they “shrink” we become thirsty. No worries. If we drink water (nothing added to it such as the flavor aides) we can restore this deficiency. The second type of thirst occurs when we are sweating, have diarrhea, vomit, or are bleeding, and is called extracellular thirst. Essentially, water is lost from the fluid surrounding our cells and drinking a saline solution helps such as Gatorade or Powerade.


14.1.6. Sex

Sexual behavior is an interesting type of motivated behavior as it is not needed for survival in the same sense as hunger or thirst but is needed for reproduction and continuation of the species. Understanding sexual behavior is important, as a 2017 survey conducted by the Centers for Disease Control and Prevention (CDC) of high school students shows:

  • 40% of students said they had sexual intercourse
  • 10% have had more than one sexual partner
  • 30% had sexual intercourse during the previous 3 months and of this, 46% did not use a condom the last time they had sex and 14% did not use any method to prevent pregnancy.
  • In terms of health outcomes, 21% of all new HIV diagnoses in the US in 2016 were people aged 13-24, half of the 20 million new STD cases in the US were people aged 15-24, and about 210,000 babies were born to girls aged 15-19 in 2016

Source: https://www.cdc.gov/healthyyouth/sexualbehaviors/

Human sexual behavior is activated by the sex hormones estrogens, progestins, and androgens. All three circulate in the blood of males and females but females have greater levels of the first two and males have higher levels of the last. Recall from Module 10 that during adolescence hormone levels rise and lead to increases in sexual desire and behavior.

According to Masters and Johnson (1966) there is a distinct pattern of physiological arousal for men and women, before, during, and after sexual activity, and called the sexual response pattern. How so? Phase 1 is excitement and is characterized by increased muscle tension, faster heart rate, the breasts becoming fuller and the nipples hardening, vaginal lubrication beginning, and the man secreting a lubricating liquid. Phase 2 is plateau and extends to the brink of orgasm and is an intensification of the changes began in phase 1. Phase 3 is orgasm and is the climax of the cycle but lasts only a few seconds. The uterus in women and the penis in men undergo rhythmic contractions, and in men results in the ejaculation of semen. For men and women, the phase is intensely pleasurable and leads to a release of both physical and psychological tension. Phase 4 is resolution and now the body returns to its normal level of functioning. Swelled or erect body parts return to normal and sexual partners experience intimacy, fatigue, and a general sense of well-being. Men enter a refractory period during which they cannot achieve an orgasm again. How long this last depends on the man and the time lengthens with age.

14.2. Substance Abuse: Motivated by a Desire to Feel Better


Section Learning Objectives

  • Define substances and substance abuse.
  • Describe properties of substance abuse.
  • Describe specific substances that can be used and abused.
  • Describe the biological causes of substance-related and addictive disorders.
  • Describe the cognitive causes of substance-related and addictive disorders.
  • Describe the behavioral causes of substance-related and addictive disorders.
  • Describe the sociocultural causes of substance-related and addictive disorders.


In this second section of Module 14, I want to discuss the issue of drug and substance abuse. At times, people choose to deal with life and all its stressor with drugs, alcohol, and/or cigarettes. Of course, they can also use comfort foods as has been discussed throughout this book. Taken together, these are tension reduction strategies, and all can become problematic if used to excess.


Please note that the content of Section 14.2.1 comes from Module 11 of Abnormal Psychology, 1st edition, by Alexis Bridley and Lee Daffin. If you wish to see the entire module, please visit:

(https://opentext.wsu.edu/abnormal-psych/chapter/module-11-substance-related-and-addictive-disorders/) and the rest of the book can be accessed through this link. Be advised I have done some editing and tailoring of this content to fit the current textbook, but the essence of the content and message is the same.


14.2.1. Substance Abuse

Substance-related disorders are among the most prevalent psychological disorders with roughly 100 million people in the United States reporting the use of an illegal substance sometime throughout their life (SAMHSA, 2014). While this disorder was previously classified as “drug abuse,” the evolvement of the disorder has sparked abuse of other substances such as alcohol, tobacco, and caffeine, thus better classifying the disorder as abuse of substances.

What are substances? Substances are any ingested materials that cause temporary cognitive, behavioral, and/or physiological symptoms within the individual. These changes that are observed directly after or within a few hours of ingestion of the substance are classified as substance intoxication (American Psychiatric Association, 2013). Substance intoxication symptoms vary greatly and are dependent on the type of substance ingested. Specific substances and their effects will be discussed later in the module.

Repeated use of these substances, or frequent substance intoxication can develop into a long-term problem known as substance abuse. Abuse occurs when an individual consumes the substance for an extended period or has to ingest large amounts of the substance to get the same effect a substance provided previously. The need to continually increase the amount of ingested substance is also known as tolerance. As tolerance builds, additional physical and psychological symptoms present, often causing significant disturbances in an individual’s personal and/or professional life. Individuals with substance abuse often spend a significant amount of time engaging in activities that revolve around their substance use, thus spending less time in recreational activities that once consumed their time. Sometimes, there is a desire to reduce or abstain from substance use, however, cravings and withdrawal symptoms often prohibit this from occurring on one’s own attempts. Common withdrawal symptoms include but are not limited to: cramps, anxiety attacks, sweating, nausea, tremors, and hallucinations. Depending on the substance and the tolerance level, most withdrawal symptoms last anywhere from a few days to a week. For those with extensive substance abuse- or multiple substances being abused- withdrawal should be closely monitored in a hospital setting to avoid serious possible consequences such as seizures, stroke, or even death.

According to the DSM-5 (APA, 2013), an individual is diagnosed with Substance Intoxication, Use, and/or Withdrawal specific to the substance(s) the individual is ingesting. While there are some subtle differences in symptoms, particularly psychological, physical, and behavioral symptoms, the general diagnostic criteria for Substance Intoxication, Use, and Withdrawal remains the same across substances. Therefore, the general diagnostic criteria for Substance Intoxication, Use, and Withdrawal are reviewed below, with more specific details of psychological, physical, and/or behavioral symptoms in the Types of Substances Abused section.

For a diagnosis of Substance Intoxication, the individual must have recently ingested a substance (APA, 2013). Immediately following the ingestion of this substance, significant behavioral and/or psychological change is observed. In addition, physical and physiological symptoms present as a direct result of the substance ingested. As stated above, these behavioral, physical and physiological symptoms are dependent on the type of substance that is ingested and therefore, discussed in more detail within each substance category (i.e., depressants, stimulants, hallucinogens/cannabis/combination).

In order to meet criteria for Substance Use Disorder, an individual must experience significant impairment or distress over the course of 12-months due to their use of a substance (APA, 2013). Distress or impairment can be described as any of the following: inability to complete or lack of participation in work, school or home obligations/activities; increased time spent on activities obtaining, using, or recovering from substance use; impairment in social or interpersonal relationships; use of substance in a potentially hazardous situation; psychological problems due to recurrent substance abuse; craving for substance; an increase in the amount of substance used over time (i.e., tolerance); difficulty reducing the amount of substance used despite desire to reduce/stop using the substance; and/or withdrawal symptoms (APA, 2013). While the number of these symptoms may vary among individuals, only two symptoms are required to be present for a diagnosis of a Substance Use Disorder.

Finally, Substance Withdrawal is diagnosed when there is cessation or reduction of a substance that has been used for a long period of time. Individuals undergoing substance withdrawal will experience physiological and/or psychological symptoms within a few hours after cessation/reduction (APA, 2013). These symptoms cause significant distress or impairment in daily functioning. Similar to Substance Intoxication, physiological and/or psychological symptoms during substance withdrawal are often specific to the substance abused and are discussed in more detail within each substance category later in the module.


14.2.2. Types of Substances Abused

The substances that are most often abused can be divided into three categories based on how they impact one’s physiological state: depressants, stimulants, and hallucinogens/cannabis/combination. Depressants. Depressant substances such as alcohol, sedative-hypnotic drugs, and opioids, are known to have a depressing, or inhibiting effect on one’s central nervous system; therefore, they are often used to alleviate tension and stress. Unfortunately, when used in large amounts, they can also impair an individual’s judgment and motor activity.

While alcohol is one of the only legal (over the counter) substances we will discuss, it is also the most commonly consumed substance. According to the 2015 National Survey on Drug Use and Health, approximately 70% of individuals drank an alcoholic beverage in the last year and nearly 56% of individuals drank an alcoholic beverage in the past month (SAMHSA, 2015). While the legal age of consumption in the United States is 21, approximately 78% of teens report that they have drank alcohol at some point in their life (SAMHSA, 2013).

Despite the legal age of consumption, many college-aged students engage in binge or heavy drinking. In fact, 45% of college age students report engaging in binge drinking, with 14% engaging in binge drinking at least 5 days per month (SAMHSA, 2013). In addition to these high levels of alcohol consumption, college age students also engage in other behaviors such as skipping meals which can impact the rate of alcohol intoxication, as well as place them at risk for dehydration, blacking out, and developing alcohol induced seizures (Piazza-Gardner & Barry, 2013).

The “effective” substance of alcohol, ethyl alcohol, is a chemical that is absorbed quickly into the blood via the lining of the stomach and intestine. Once in the blood stream, ethyl alcohol travels to the central nervous system (i.e., brain and spinal cord) and produces depressive symptoms such as impaired reaction time, disorientation, and slurred speech. These symptoms are produced due to the ethyl alcohol binding to GABA receptors, thus preventing GABA from providing inhibitory messages and allowing the individual to relax (Filip et al., 2015).

The effect of ethyl alcohol in moderation allows for an individual to relax, engage more easily in conversation, and in general, produces a confident and happy personality. However, when consumption is increased or excessive in nature, the central nervous system is unable to adequately metabolize the ethyl alcohol, and negative effects begin to present. Symptoms such as blurred vision, difficulty walking, slurred speech, slowed reaction time, and sometimes, aggressive behaviors are observed.

The extent to which these symptoms present are directly related to the concentration of ethyl alcohol within the body, as well as the individual’s ability to metabolize the ethyl alcohol. There are a lot of factors that contribute to how quickly one’s body can metabolize ethyl alcohol. Food, gender, body weight, and medications are among the most common factors that affect alcohol absorption (NIAAA,1997). More specifically, recent consumption of food, particularly food high in fat and carbohydrates, slows the absorption rate of ethyl alcohol, thus reducing its effects. With regards to gender, women absorb and metabolize alcohol differently than men, likely due to the smaller amount of body water and the lower activity of an alcohol metabolizing enzyme in the stomach. Another factor related to gender is body weight- with individuals with more body mass metabolizing the alcohol at a slower rate than those who weigh less. Finally, various medications, both over the counter and prescription based can impact the liver’s ability to metabolize alcohol, thus impacting the severity of symptoms that present (NIAAA, 1997).

Sedative-Hypnotic drugs, more commonly known as anxiolytic drugs, have a calming and relaxing effect on individuals. When used at a clinically effective amount, they can have a sedative effect, thus making them an appropriate drug for treating anxiety related disorders. In the early 1900’s, barbiturates were introduced as the main sedative and hypnotic drug; however, due to their addictive nature, as well as respiratory distress when consumed in large amounts, they have been largely replaced by benzodiazepines which are considered a safer alternative as they have fewer addictive qualities (Filip et al., 2014)

Commonly prescribed benzodiazepines— Xanex, Ativan, and Valium—have a similar effect to alcohol as they too bind to the GABA receptors and increase GABA activity (Filip et al., 2014). This increase in GABA produces a sedative and calming effect. Benzodiazepines can be prescribed for both temporary (relief anxiety on flight or prior to surgery) or long-term use (generalized anxiety disorder). While they do not produce respiratory distress in large dosages like barbiturates, they can cause intoxication and addictive behaviors due to their effects on tolerance.

Opioids are naturally occurring, derived from the sap of the opium poppy. In the early 1800’s, morphine was isolated from opium by German chemist Friedrich Wihelm Adam Serturner. Due to its analgesic effect, it was named after the Greek god of dreams, Morpheus (Brownstein, 1993). Its popularity grew during the Civil War as it was the primary medication given to soldiers with battle injuries. Unfortunately, this is also when the addictive nature of the medication was discovered, as many soldiers developed “Soldier’s Disease” as a response to tolerance of the drug (Casey, 1978).

In an effort to alleviate the addictive nature of morphine, heroin was synthesized by the German chemical company Bayer in 1898, and was offered in a cough suppressant (Yes, Bayer promoted Heroin). For years, heroin remained in cough suppressants as well as other pain reducers until it was discovered that heroin was actually more addictive than morphine. In 1917, Congress identified that all drugs derived from opium were addictive, thus banning the use of opioids in over-the-counter medications.

Opioids are unique in that they provide both euphoria and drowsiness. Tolerance to these drugs builds quickly, thus resulting in an increased need of the medication to produce desired effects. This rapid tolerance is also likely responsible for opioids highly addictive nature. Opioid withdrawal symptoms can range from restlessness, muscle pain, fatigue, anxiety, and insomnia. Unfortunately, these withdrawal symptoms, as well as intense cravings for the drug can persist for several months, with some reports up to years. Because of the intensity and longevity of these withdrawal symptoms, many individuals struggle to remain abstinent, and accidental overdoses are common (CDC, 2013).

The rise of abuse and misuse of opioid products in the early-to-mid 2000s is a direct result of the increased number of opioid prescription medications containing oxycodone and hydrocodone (Jayawant & Balkrishnana, 2005). The 2015 report estimated 12.5 million Americans were abusing prescription narcotic pain relievers in the past year (SAMHSA, 2016). In efforts to reduce the abuse of these medications, the FDA developed programs to educate prescribers about the risks of misuse and abuse of opioid medications. Stimulants. The two most common types of stimulants abused are cocaine and amphetamines. Unlike depressants that reduce the activity of the central nervous system, stimulants have the opposite effect, increasing the activity in the central nervous system. Physiological changes that occur with stimulants are increased blood pressure, heart rate, pressured thinking/speaking, and rapid, often jerky behaviors. Because of these symptoms, stimulants are often used for their feelings of euphoria, to reduce appetite, and prevent sleep.

Similar to opioids, cocaine is extracted from a South American plant- the coca plant- and produces feelings of energy and euphoria. It is the most powerful natural stimulant known to date (Acosta et al., 2011). As stated, low doses can produce feelings of excitement, talkativeness, and euphoria; however, as the amount of ingested cocaine increases, physiological changes such as rapid breathing, increased blood pressure, and excessive arousal can be observed. The psychological and physiological changes from cocaine are due to an increase of dopamine, norepinephrine and serotonin in various brain structures (Haile, 2012; Hart & Ksir, 2014).

One key feature of cocaine use is the rapid high of cocaine intoxication, followed by the rapid letdown, or crashing, as the drug diminishes within the body. During the euphoric intoxication, individuals will experience poor muscle coordination, grandiosity, compulsive behavior, aggression, and possible hallucinations and/or delusions (Haile, 2012). Conversely, as the drug leaves the system, the individual will experience negative effects such as headaches, dizziness, and fainting (Acosta et al., 2011). These negative feelings often produce a negative feedback loop, encouraging individuals to ingest more cocaine to alleviate the negative symptoms. This also increases the change of accidental overdose.

Cocaine is unique in that it can be ingested in various ways. While cocaine was initially snorted via the nasal cavity, individuals found that if the drug was smoked or injected, it’s effects were more powerful and longer lasting (Haile, 2012). The most common way cocaine is currently ingested is via freebasing, which involves heating cocaine with ammonia to extract the cocaine base. This method produces a form of cocaine that is almost 100 percent pure. Due to its low melting point, freebased cocaine is easy to smoke via a glass pipe. Inhaled cocaine is absorbed into the blood stream and brain within 10-15 seconds suggesting its effects are felt almost immediately (Addiction Centers of America).

Crack is a derivative of cocaine that is formed by combining cocaine with water and another substance (commonly baking soda) to create a solid structure that is then broken into smaller pieces. Because of this process, it requires very little cocaine to make crack, thus making it a more affordable drug. Coined for the crackling sound that is produced when it is smoked, it is also highly addictive, likely due to the fast-acting nature of the drug. While the effects of cocaine peak in 20-30 minutes and last for about 1-2 hours, the effects of crack peak in 3-5 minutes and last only for up to 60 minutes (Addiction Centers of America).

Amphetamines are manufactured in a laboratory setting. Currently, the most common amphetamines are prescription medications such as Ritalin, Adderall, and Dexedrine (prescribed for sleep disorders). These medications produce an increase in energy and alertness and reduce appetite when taken at clinical levels; however, when consumed at larger dosages, it can produce intoxication similar to psychosis, including violent behaviors. Due to the increased energy levels and appetite suppressant qualities, these medications are often abused by students studying for exams, athletes needing extra energy, and individuals seeking weight loss (Haile, 2012). Biologically, similar to cocaine, amphetamines effect the central nervous system by increasing the amount of dopamine, norepinephrine, and serotonin in the brain (Haile, 2012).

Methamphetamine, a derivative of amphetamine, is often abused due to its low cost and feelings of euphoria and confidence; however, it can have serious health consequences such as heart and lung damage (Hauer, 2010). Most commonly used intravenously or nasally, methamphetamine can also be eaten or heated to a temperature in which it can be smoked. The most notable effects of methamphetamine use are the drastic physical changes to one’s appearance including significant teeth damage and facial lesions (Rusyniak, 2011).

While I’m sure you all are well aware of how caffeine is consumed, you may be surprised to learn that in addition to coffee, energy drinks, and soft drinks, caffeine can also be found in chocolate and tea. Because of the vast use of caffeine, it is the most widely consumed substance in the world, with approximately 90% of Americans consuming some type of caffeine every day (Fulgoni, Keast, & Lieberman, 2015). While caffeine is often consumed in moderate dosages, caffeine intoxication and withdrawal can occur. In fact, an increase in caffeine intoxication and withdrawal has been observed with the simultaneous popularity of energy drinks. Common energy drinks such as Monster and RedBull have nearly double the amount of caffeine of tea and soda (Bigard, 2010). While these drinks are commonly consumed by adults, a startling 30% of middle and high schoolers also report regular consumption of energy drinks to assist with academic and athletic responsibilities (Terry-McElrath, O’Malley, & Johnston, 2014). The rapid increase in caffeinated beverages has led to an increase in ER visits due to the intoxication effects (SAMHSA, 2013). Hallucinogens/Cannabis/Combination. The final category includes both hallucinogens and cannabis- both of which produce sensory changes after ingestion. While hallucinogens are known for their ability to produce more severe delusions and hallucinations, cannabis also has the capability of producing delusions or hallucinations, however, this typically occurs only when large amounts of cannabis are ingested. More commonly, cannabis has been known to have stimulant and depressive effects, thus classifying itself in a group of its own due to the many different effects of the substance.

Hallucinogens come from natural sources and have been involved in cultural and religious ceremonies for thousands of years. Synthetic forms of hallucinogens have also been created- most common of which are PCP, Ketamine, LSD and Ecstasy. In general, hallucinogens produce powerful changes in sensory perception. Depending on the type of drug ingested, effects can range from hallucinations, changes in color perception, or distortion of objects. Additionally, some individuals report enhanced auditory, as well as changes in physical perception such as tingling or numbness of limbs and interchanging hot and cold sensations (Weaver & Schnoll, 2008). Interestingly, the effect of hallucinogens can vary both between individuals, as well as within the same individual. This means that the same amount of the same drug may produce a positive experience one time, but a negative experience the next time.

Overall, hallucinogens do not have addictive qualities; however, individuals can build a tolerance, thus needing larger quantities to produce similar effects (Wu, Ringwalt, Weiss, & Blazer, 2009). Furthermore, there is some evidence that long term use of these drugs results in psychosis, mood, or anxiety disorders due to the neurobiological changes after using hallucinogens (Weaver & Schnoll, 2008).

Similar to hallucinogens and a few other substances, cannabis is also derived from a natural plant- the hemp plant. While the most powerful of hemp plants is hashish, the most commonly known type of cannabis, marijuana, is a mixture of hemp leaves, buds, and tops of plants (SAMHSA, 2014). The potency of cannabis is impacted by many external factors such as the climate it was grown in, the way the cannabis was prepared, and the duration of storage. Of the active chemicals within cannabis, tetrahydrocannabinol (THC) appears to be the single component that determines the potent nature of the drug. Various strains of marijuana have varying amounts of THC; hashish contains a high concentration of THC, while marijuana has a small concentration.

THC binds to cannabinoid receptors in the brain which produces psychoactive effects. These effects vary depending on both an individual’s body chemistry, as well as various strains and concentrations of THC. Most commonly, people report feelings of calm and peace, relaxation, increased hunger, and pain relief. Occasionally, negative symptoms such as increased anxiety or paranoia, dizziness, and increased heart rate also occur. In rare cases, individuals develop psychotic symptoms or schizophrenia following cannabis use (Donoghue et al., 2014).

While nearly 20 million Americans report regular use of marijuana, only ten percent of these individuals will develop a dependence on the drug (SAMHSA, 2013). Of particular concern is the number of adolescents engaging in cannabis use. One in eight 8th graders, one in four 10th graders, and one in three 12th graders report use of marijuana in the past year (American Academy of Child and Adolescent Psychiatry, 2013). Individuals who begin cannabis abuse during adolescence are at an increased risk to develop cognitive effects from the drug due to the critical period of brain development during adolescence (Gruber, Sagar, Dahlgren, Racine, & Lukas, 2012). Increased discussion about the effects of marijuana use, as well as psychoeducation about substance abuse in general is important in preventing marijuana use during adolescence.

It is not uncommon for substance abusers to consume more than one type of substance at a time. This combination of substance use can have dangerous results depending on the interactions between substances. For example, if multiple depressant drugs (i.e., alcohol and benzodiazepines and/or opiates) are consumed at one time, an individual is at risk for severe respiratory distress or even death, due to the compounding depressive effects on the central nervous system. Additionally, when an individual is under the influence of one substance, judgement may be impaired, and ingestion of a larger amount of another drug may lead to an accidental overdose. Finally, the use of one drug to counteract the effects of another drug—taking a depressant to combat the effects of a stimulant—is equally as dangerous as the body is unable to regulate homeostasis.


14.2.3. Etiology of Substance Related and Addictive Disorders Biological – Genetics. Similar to other mental health disorders, substance abuse is genetically influenced.  With that said, it is different than other mental health disorders in that if the individual is not exposed to the substance, they will not develop substance abuse.

Heritability of alcohol is among the most well studied substances, likely due to the fact that it is the only legal substance (with the exception of cannabis in some states). Twin studies have indicated a range of 50-60% heritability risk for alcohol disorder (Kendler et al., 1997). More recent studies exploring the heritability of other substance abuse, particularly drug use, suggests there may be a stronger heritability link than previously thought (Jang, Livesley, & Vernon, 1995). Twin studies indicate that the genetic component of drug abuse is stronger than drug use in general, meaning that genetic factors are more significant for abuse of a substance over nonproblematic use (Tsuang et al., 1996). Merikangas and colleagues (1998) found an 8-fold increased risk for developing a substance abuse disorder across a wide range of substances.

Unique to substance abuse is the fact that both genetic and familial influence are both at play. What does this mean? Well, biologically, the individual may be genetically predisposed to substance abuse; additionally, the individual may also be at risk due to their familial environment where their parents and/or siblings are also engaging in substance abuse. Individuals whose parents abuse substances may have a greater opportunity to ingest substances, thus promoting drug-seeking behaviors. Furthermore, families with a history of substance abuse may have a more accepting attitude of drug use than families with no history of substance abuse (Leventhal & Schmitz, 2006). Biological – Neurobiological. A longstanding belief about how drug abuse begins and is maintained is the brain reward system. A reward can be defined as any event that increases the likelihood of a response and has a pleasurable effect. Majority of research on the brain reward system has focused on the mesocorticolimbic dopamine system, as it appears this area is the primary reward system of most substances that are abused. As research has evolved in the field of substance abuse, five additional neurotransmitters have also been implicated in the reinforcing effect of addiction: dopamine, opioid peptides, GABA, serotonin, and endocannabinoids. More specifically, dopamine is less involved in opioid, alcohol, and cannabis. Alcohol and benzodiazepines lower the production of GABA, while cocaine and amphetamines are involved in the lowering of dopamine. Cannabis has been shown to reduce the production of endocannabinoids. Cognitive. Cognitive theorists have focused on the beliefs regarding the anticipated effects of substance use. Defined as the expectancy effect, drug-seeking behavior is presumably motivated by the desire to attain a particular outcome by ingesting a substance. The expectancy effect can be defined in both positive and negative forms. Positive expectations are thought to increase drug-seeking behavior, while negative experiences would decrease substance use (Oei & Morawska, 2004). Several alcohol studies have examined the expectancy effect on the use of alcohol. Those with alcohol abuse reported expectations of tension reduction, enhanced sexual experiences, and improved social pleasure (Brown, 1985). Additionally, observing positive experiences, both in person and through television or social media also shapes our drug use expectancies.

While some studies have explored the impact of negative expectancy as a way to eliminate substance abuse, research has failed to continually support this theory, suggesting that positive experiences and expectations are a more powerful motivator of substance abuse than the negative experiences (Jones, Corbin, Fromme, 2001). Behavioral. Operant conditioning has been implicated in the role of developing substance use disorders. As you may remember, operant conditioning refers to the increase or decrease of a behavior, due to a reinforcement or punishment. Since we are talking about increasing substance use, behavioral theorists suggest that substance abuse is positively and negatively reinforced due to the effects of a substance.

Positive reinforcement occurs when the substance use is increased due to the positive or pleasurable experiences of the substance. More specifically, the rewarding effect or pleasurable experiences while under the influence of various substances directly impacts the likelihood that the individual will use the substance again (Wise & Koob, 2013). Studies of substance use on animals routinely supports this theory as animals will work to receive injections of various drugs (Wise & Koob, 2013).

Negative reinforcement, or the increase of a given behavior due to the removal of a negative effect, also plays a role in substance abuse in two different ways. First, many people ingest a substance as an escape from their unpleasant life- whether it be physical pain, stress, or anxiety, to name a few. Therefore, the substance temporarily provides relief from a negative environment, thus reinforcing future substance abuse (Wise & Koob, 2013). The second way negative reinforcement is involved in substance abuse is during symptoms of withdrawal. As previously mentioned, withdrawal from a substance often produces significant negative symptoms such as nausea, vomiting, uncontrollable shaking, etc. To eliminate these symptoms, and individual will consume more of the substance, thus again escaping the negative symptoms and enjoying the “highs” of the substance.  Sociocultural. Arguably, one of the strongest influences of substance abuse is the impact of one’s friends and immediate environment. Peer attitudes, perception of one’s friend’s drug use, pressure from peers to use substances, and beliefs about substance use are among the strongest predictors of drug use patterns (Leventhal & Schmitz, 2006). This is particularly concerning during adolescence when patterns of substance use typically begin.

Additionally, research continually supports a strong relationship between second generation substance abusers (Wilens et al., 2014). The increased likelihood of family members substance abuse is likely related to both a genetic predisposition, as well as the accepting attitude of the familial environment (Chung et al., 2014). Not only does a child have early exposure to these substances if their parent has as substance abuse problem, but they are also less likely to have parental supervision which may impact their decision related to substance use (Wagner et al., 2012). One potential protective factor against substance use is religiosity. More specifically, families that promote religiosity may reduce substance use by promoting negative experiences (Galen & Rogers, 2004).

Another sociocultural view on substance abuse is stressful life events, particularly those related to financial stability. Prevalence rates of substance abuse is higher in poorer people (SAMHSA, 2014). Furthermore, additional stressors such as childhood abuse/trauma, negative work environments, as well as discrimination are also believed to contribute to the development of a substance use disorder (Hurd, Varner, Caldwell, & Zimmerman, 2014; McCabe, Wilsnack, West, & Boyd, 2010; Unger et al., 2014). 

Module Recap

Module 14 presented you with a second way that internal forces motivate behavior. In this case, we discussed physiological processes involving drives and addicted behavior. Drives included hunger, thirst, temperature, sex, and sleep. We explored the various ways the brain and other systems cause motivated behavior to restore homeostasis and in the case of hunger, how external signals factor in too. We looked at addiction from the perspective of clinical psychology and you could re-examine the process of change, and what DiClemente had to say, from Module 6.

With that, the core content of the textbook is covered. To round things out, I will engage in a brief discussion of motivated behavior, for better or worse, and offer an explanation in terms of universal human values in Module 15.

2nd edition


Creative Commons License
Module 14: Motivation and Physiological Psychology by Lee William Daffin Jr. is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

Share This Book