Internal Stimuli: Examples and Definition

The term ‘internal stimuli’ (singular: internal stimulus) refers to the biological or psychological experiences that occur from within a person or organism.

Examples include changes in biological states that indicate the need for sleep or food, or a person’s thoughts and feelings that occur at the conscious or nonconscious level.

Cognitive psychology has demonstrated wide-spread applications of the study of mental processes, ranging from understanding various psychological disorders (such as depression) to the formation of attitudes and persuasion in consumer behavior.

The role of internal stimuli in human behavior is represented by the S-O-R model proposed by Woodworth (1929).

The model stands for stimulus-organism-response. Woodworth noted that factors within the organism affect its response.

Types of Internal Stimuli

There are several types of internal stimuli, outlined below.

1. Physiological: Physiological stimuli involve changes in biological states. The human body operates on the basis of homeostasis, which tries to keep the body at a state of equilibrium. Homeostasis maintains adequate oxygen levels, blood sugar, and internal temperature. Changes in equilibrium trigger internal cues such as the need to sleep, cool or warm the body, ingest nutrition, or seek medical attention.
2. Sensory: Although sensations derive externally, they are encoded via the 5 sensory modalities, which can then influence the organism’s behavior. Additionally, not all sensations will be interpreted the same. Different cognition-based interpretations means that each individual may have slightly different reactions to the same external stimuli. For example, listening to loud music may be enjoyable to some, but be quite an aversive experience to others.
3. Cognitive: Some forms of internal stimuli emanate from mental processes involved in the acquisition and manipulation of information. For example, when problem-solving, a person may have an internal “feel” for when a solution will work or not. This is often based on experience and allows a person to “just know.” 
4. Affective: Emotions are internal stimuli that can impact behavior. For example, internal emotional states such as fear, anxiety, excitement or joy can alter behavior in dramatic ways. Increasing awareness of these types of internal stimuli can help reduce stress, manage anger and anxiety, or improve mental concentration.

Internal Stimuli Examples

• Generalized State of Anxiety: Some people are in a near continuous state of feeling anxious. This involves elevated heart and respiration rates that create internal sensations that can make them weary of unfamiliar people, places, and things.
• Feeling Hot: If located in an exceptionally warm environment without temperature control, the body will begin to overheat. This creates an internal cue for the organism to seek a cooler environment.
• Being Bored: The lack of cognitive engagement and mental processing can create a sense of boredom. The mind needs stimulation. A person might become aware of this internal cue and seek outward stimulation by reading a book or watching television.
• The Fight-or-Flight Response: The sudden activation of the sympathetic nervous system in response to an external stimulus activates several internal biological responses. These biological reactions serve as internal stimuli to inform the organism of impending danger.
• Needing Hydration: After exercising and perspiring for an extended period of time, the body will reach a state of disequilibrium. This serves as an internal cue to seek hydration.
• The Gut Instinct: Getting a feeling that something just “feels” right or wrong is a kind of internal stimulus that helps us make decisions. The feeling is not based purely on facts and logical analysis, but seems more like an instinctive 6^th-sense.
• Reproductive Drives: All animal species have hormonal driven biological urges to procreate. These drive states are internal cues to engage in certain behaviors that will propagate the species.  
• Feelings of Loneliness: Many people experience feelings of loneliness if they undergo long periods of time without interacting with others.
• Nausea: Although this internal stimulus may be caused by an external stimulus such as spoiled food or poison, the sensation and compulsion to expel the ingested item is driven internally.  
• Intrinsic Motivation: The pursuit of goals and accomplishments can stem from an individual’s need to achieve or personal aspirations. The pay-off is an intrinsic reward.

Internal vs External Stimuli

	Internal Stimuli	External Stimuli
Definition	These are stimuli that originate from within the organism.	These are stimuli that originate from the environment outside the organism.
Examples	Hunger, thirst, pain, emotions like fear or happiness.	Light, sound, temperature, pressure, chemical changes.
Response	Usually results in physiological responses like eating, drinking, or changes in mood.	Often results in behavioral responses like moving towards or away from the stimulus.
Detection	Detected through internal body systems and processes such as the nervous and endocrine systems.	Detected through the sensory organs like eyes, ears, skin, tongue, and nose.
Impact on Survival	Critical for maintaining homeostasis and overall health.	Essential for the organism’s interaction with the environment, for finding food, avoiding danger, etc.
Influence on Behavior	Can influence behavior based on physiological needs and emotional states.	Can influence behavior based on environmental cues and conditions.
Role in Learning & Memory	Crucial for associative learning, such as conditioning hunger cues to specific times or situations.	Important for classical and operant conditioning, learning to associate certain external cues with specific outcomes.

Applications of Internal Stimulus Research

1. Mindfulness and Meditation

Mindfulness is the practice of learning how to increase awareness of the present moment, which includes being in tune with one’s internal states, sensations, and thoughts. Meditation has a similar goal of focusing one’s attention inward.

Increasing awareness of what is happening internally can help a person feel more grounded. It can also help them become more aware of thinking processes or situations that cause anxiety.

Mindfulness activities can be performed while walking in a park, engaged in routine activities such as cleaning or bathing, or in more formal situations that involve meditation.

A recent study involving over 500 secondary students in the UK found that participants in mindfulness training reported fewer depressive symptoms, lower stress, and greater wellbeing than nonparticipants (Kuyken et al., 2013)

2. In Keeping a Diet

Sometimes people misinterpret feeling bored with being hungry. This can lead to impulse eating, which usually involves consumption of salty snacks or other unhealthy food.

Helping people learn how to distinguish between these two internal states is a key first step to maintaining a diet.

3. In Potty Training

Heling children become aware of their bodily sensations is a key step in potty training. This is called interoception.

Interoception is more formally defined as the ability to interpret the body’s physical signals that indicate hunger, thirst, being hot or cold, or other sensations such as feeling calm or scared.

Being able to recognize the sensations associated with a full bladder or bowel is essential to helping children develop control over these bodily functions. 

4. In Self-Regulation

Baumeister et al. (2007) define self-regulation as “the self altering its own responses or inner states.” This includes regulating impulses and the ability to delay gratification.

This is accomplished through the self operating as an executive function. It monitors the individual’s behavior and inner stimuli such as feelings of impulsiveness and desire.

It then regulates behavior that stem from those impulses by “overriding one response or behavior and replacing it with a less common but more desired response.”

5. In Cognitive-Behavioral Therapy (CBT)

Cognitive behavioral therapy (CBT) is a treatment for various psychological disorders related to depression and anxiety. CBT starts with the premise that cognitive distortions are key drivers of maladaptive behavior.

Cognitive distortions can include overgeneralizing failure, magnifying negatives, and catastrophizing (see more examples of cognitive distortions here).

As Beck (1995) stated,

“In a nutshell, the cognitive model proposes that distorted or dysfunctional thinking (which influences the patient’s mood and behavior) is common to all psychological disturbances” (p. 1).

Helping a patient increase their awareness of the presence of these thought patterns is the first step in teaching them how to challenge the underlying assumptions of those distortions.

In addition to depression and anxiety disorders, CBT has expanded to the treatment of marital issues, eating disorders, and substance abuse.

6. As Inspiration for Artistic Expression

The inspiration for song lyrics, musical compositions, and creative novels often comes from within. The internal conflicts that arise when grappling with life’s disappointments or the heartache of lost love can become the impetus of a great song that touches the hearts of millions of listeners.

Daydreams and a rich fantasy life can help the author put pen to paper and generate a fascinating science fiction novel or murder mystery that captivates the minds of millions of readers.

These are all examples of internal stimuli that can drive artistic expression.

7. In Inspiration to Fight Injustice

Injustice comes in many forms. It can consist of gender, racial, or ethnic inequalities. Although specific events of mistreatment occur externally, the feelings of sadness, despair, and yes, anger, are as deeply internal as can be.

Those feelings can serve as the internal stimuli that compels an individual to take action. Whether it be protesting or legal action, the goal is the same; to restore equity. When that has been achieved, satisfaction and pride will be the internal stimuli that signal the fight was worth it.

Conclusion

Internal stimuli can come in many forms, from physiological sensations of hunger and thirst, to the gut instinct that informs our judgment.

We see examples of internal stimuli that are involved in CBT to help individuals overcome depression or anxiety. In other scenarios CBT can help an individual exert control over unhealthy impulses.

Increasing awareness of internal bodily signals is central to both mindfulness training and helping toddlers control their bodily functions.

Feelings of anger as result of experiencing injustice serve as an internal cue that can be so strong it compels people to take action in ways that shape history.  

Other forms of internal stimuli can become the foundation of great artistic endeavors such as writing a beautiful song or writing a titillating novel.

References

Bandura, A. (1977). Social learning theory. Prentice Hall.

Baumeister, R. F., Schmeichel, B. J., & Vohs, K. D. (2007). Self-regulation and the executive function: The self as controlling agent. Social Psychology: Handbook of Basic Principles, 2, 516-539.

Beck, J. S. (1995). Cognitive therapy: Basics and beyond. New York: Guilford Press

Craske, M. G. (2010). Cognitive–behavioral therapy. American Psychological Association.

Hyland, T. (2015). On the contemporary applications of mindfulness: Some implications for education. Journal of Philosophy of Education, 49(2), 170-186.

Kuyken, W., Weare, K., Ukoumunne, O. C., Vicary, R., Motton, N., Burnett, R., Cullen, C., Hennelly, S. and Huppert, F. (2013) Effectiveness of the Mindfulness in Schools Programme: Non-randomised controlled feasibility study. The British Journal of Psychiatry, 203, 126– 131.

Pavlov, I.P. Conditioned reflexes. London: Oxford University Press; 1927.

Woodworth, R. S. (1929). Psychology (revised edition). Henry Holt & Co., New York. https://www.sciencedirect.com/science/article/pii/S0190740920322052

Watson, J. B. (1913). Psychology as the behaviorist views it. Psychological Review, 20(2), 158-177.