Mood and Affect: Definitions and Basic Concepts

If you’ve come to this website and are reading this article, the odds are good that you or someone that you know has been diagnosed with a mood disorder.  You might be seeking more information about emotional illnesses.   But before diving into any of the numerous areas of research presented at our site, what if we pause and ask a very basic but important question:  what are moods?  We use this term all the time, but do we truly understand what they consist of and why we experience them?  Even more fuzzy, what about the term, ‘affects’?  We specialize in the treatment of ‘affective illness’ here, but what is an affect and how is it different from a mood?  This brief review will summarize a generally accepted concept of emotions, describe their composition and functional purpose and present current research in this area.  To start, let’s begin by taking a look at how these terms are currently used in clinical practice.

Current thinking defines mood as an emotional state with relative persistence over time.  Affects, in contrast, are shorter, more reactive emotional experiences.  Psychiatry and psychology trainees all learn how to describe affect in terms of degree (standard vs. reduced, blunted or flat), range (full vs. restricted) and congruence (does it fit with what the person is talking about at that moment?).  The problem here is that the definitions are circular – mood and affect are explained by emotion, and emotion is referenced to mood and affect – and the descriptions are limited.  It doesn’t really help us understand the true nature of mood, affect or emotion.  Greater insight into this problem is achieved only by turning to other areas of science that put human emotional experience into perspective:  evolution, child development, animal research, and temperament.

In his book, The Expression of the Emotions in Man and Animals, Charles Darwin made several observations that laid a foundation for the scientific study of emotion [1].  First, he noted that facial and behavioral expression of emotions were similar between species, especially between non-human primates and humans.  In response to a predator, for example, dogs, chimps and humans would all react with raised eyebrows, widely open eyes, hair standing on end (piloerection) increased heart rate, heightened muscular tone, and behavioral withdrawal.  He thus reasoned that the emotional response system in mammals is genetically inherited and evolutionarily ancient.  Second, he proposed that emotional expression consisted of particular states of mind that were combined with defined patterns of activity.  Fear was coupled with withdrawal and the above autonomic nervous system changes (increased heart rate, heightened blood pressure, cortisol secretion, etc..).  Love was linked to behavioral approach.  This identification of a motor (i.e., movement) component of emotional experience was huge.  Last, he suggested that human facial displays of emotion are the vestiges of evolutionarily earlier, stimuli-specific, whole-body response patterns.  So instead of fleeing in response to all threats, humans have learned to initially respond with a facial display of fear; instead of attacking when we are angry, we manifest only pursed lips and a tightening of certain other facial muscles.  Inherent in these descriptions is the idea that emotional displays, like the older, more global behavioral response patterns from which they derive, are also adaptations to the environment.  Survival also moves us to seek out nourishment and love from our environment.   Darwin’s contribution to the study of emotion cannot be overstated.  He recognized its inherited nature, its subjective/psychological, autonomic and motoric components, the reactive quality of these psycho-motor patterns to specific, environmental stimuli, and the communicative and adaptive purpose of emotional experience.

Approaching this subject from a developmental and cross-cultural perspective, psychologist Sylvan Tomkins has studied facial expressions in early childhood [2].   After reviewing thousands of facial expressions in newborns from many different cultures, Tomkins concluded that the face is, in effect, the primary organ of emotion.  It is the first responder and, as such, guides and leads the autonomic, other motoric, and subjective elements identified by Darwin.  Furthermore, just as Darwin noted similar behavioral emotional responses among all mammals, Tomkins found that there is a discrete number of common facial configurations used across all human societies.  Whether an African tribesman or an urban Asian baby, each person shares the same basic vocabulary of facial expressions.  He identified nine basic facial expressions that are innate, that is, present at birth, and found throughout the world.  To really bring this home, check out the Tomkin’s Institute website that shows this universal language of the face: (  These include two positive forms (interest-excitement and enjoyment-joy) and seven negative varieties (distress-anguish, anger-rage, fear-terror, shame-humiliation, disgust, and others).  Complementing Darwin’s work, Tomkins believed that these innate facial displays are automatic responses to environmental stimuli.  Further, he suggested that these early, automatic reactions form the foundation for later emotional experience.  In other words, the involuntary look of terror that comes on an infant’s face in response to a barking dog is the first component of what will become that young child’s and later adult’s experience of anxiety.

The extraordinary research of veterinarian scientist, Jaak Panksepp, grounds the theories of Darwin and Tomkins in neurobiology [3, 4].  In work that spans a forty-year career, Panksepp used electrical stimulation and lesion methods (kill certain brain cells and study behavioral effects) to identify the discrete affects experienced by a variety of mammals and their distinct neurobiological underpinnings.  Electrically stimulating one pathway produces fear and withdrawal; buzzing another results in rage; chemically lesioning a third results in the elimination of a specific emotional reaction.  His findings converge with and enhance the evolutionary and developmental perspectives.  Like Darwin and Tomkins, Panksepp’s animal work confirms the existence of a finite number of affective behavioral reactions.  Using capital letters to identify them as systems, these included: LUST, CARE, PANIC, PLAY, FEAR, RAGE, and SEEKING.  These systems have a rough, but imperfect correspondence to the core facial expressions put forward by Tomkins.  More interesting, the circuit mapping revealed that each of these primary affects was associated with their own individual neural pathways, often using specific neurotransmitters within that pathway.  Panksepp’s animal research establishes the hard-wired, neurobiological foundation of affective experience.  Thus, affects take shape as inborn, composite reaction patterns, set off by, and specific to, particular environmental stimuli, which are mediated by evolutionarily old, emotion-specific brain pathways.  We now have a much richer explanation and description of affects.  What about mood?

Freud, and more recently Michael Basch, wrestled with the issue of moods and their relationship to affects [5, 6].  Both considered moods to represent a more refined, developmentally mature expression of affects.  Basch, in particular, posited a developmental line of affective experience that begins with the type of brief, affective reactions described earlier, progresses to emotional experiences that reference an emerging sense of self, and culminate in the capacity for empathy.  Thus, developmentally, emotions proceed from a primal, unreflective, “ouch!” and withdrawal in response to pain, to a more personalized, “that hurts me” level of expression, and finally to the empathic realization that others experience pain in similar ways to oneself.  In parallel with this developmental progression, the time course of emotions begins to extend and longer-lasting mood states develop.  These longer mood stretches begin to color and influence our personalities.  When repeated reactions of fear linger, we become anxious individuals.  Affective reactions of sadness that recur and extend into frequent mood states begin to impart a blue tone to one’s personality.  That sequence makes sense.  But what of the reverse direction?  Can attributes of personality shape the nature of our emotional inclinations?   Experimental studies in this area form the last section of this report.

The research of Richard Davidson, a psychologist at the University of Wisconsin – Madison, was prompted by individual differences in emotional expression.  Why do some people incline towards brighter, more outgoing moods and others, towards a more brooding and pessimistic style?  Davidson suggested these differences arise from one’s underlying, affective style – this is his term for a broad dispositional temperament that biases individuals towards specific affective and mood experiences [7].  Affective style describes an individual’s tendencies to respond to particular stimuli in specific ways.  For example, mild surprises might typically elicit laughter in one person, but a startle reaction in another.  These characteristic reactions can be measured based on magnitude (how much does one laugh or get startled?), duration, threshold (how large a stimulus is necessary to prompt the reaction?), peak to rise (does the reaction jump up quickly or does it percolate upwards?), and recovery time.  This breakdown of affective responses into its constituent components was termed affective chronometry – a truly fascinating field in its own right.  Now, let’s go back to the topic of affective style.

It turns out that affective style correlates broadly with two fundamental neurological orientation systems that cause us to respond in habitual ways towards environmental events.  The operation of the Behavioral Activating System (BAS) and the Behavioral Inhibition System (BIS) – recently discussed in depth by Dr. Stern in her blog at this site – act as motor biases that slant us towards and away from rewarding and aversive stimuli respectively.  Think about it like posture:  imagine one person with an upright, erect stance who handles things in an assertive, proactive way and another with hunched over shoulders and a slouch who is waiting for life’s next disappointment.

The BAS moves us towards desired goals and favored outcomes, the BIS causes us to recoil from threats and losses.   High BAS individuals are prone to extraversion and impulsivity.  Impaired BAS system functioning is associated with the resignation and the joylessness of depression.  High BIS activity is associated with anxious apprehension and avoidance, whereas deficient BIS would present as disinhibition and recklessness.

Davidson first demonstrated that affective style correlates with the activity of these two fundamental motivational systems.  His later research had two blockbuster findings.  First, the optimistic, challenge-embracing, high BAS orientation is associated with increased left frontal brain wave activity that is measured by EEG (electroencephalogram; a device which measures brain waves).  Conversely, the fearful, depressed high BIS inclination matches up with high right frontal EEG activity.  Therefore, whichever side of the front part of our brain is more active appears to shape our outlook and dispositional mood.  Second, these brainwave activity asymmetries are present from birth onward.  Davidson found, for example, that 10 month old infants who cried in response to maternal separation had higher right than left prefrontal EEG activity.  Not only are these differences present from an early age, they are stable over time.

Thus, we are born with a basic, hard-wired, orientational preference to respond to some events more so than others, and in particular ways.  These neurobiological biases predispose us towards certain affective reactions.  Affect is the rapid, automatic, involuntary and adaptive response to some environmental occurrence.  The repeated experience and lingering persistence of these higher-probability reactions generates the more developmentally mature, longer-term moods that we experience.  Finally, the persistence of the mood states themselves invariably gives color to our emotional personalities.

Moods are complicated.  This review has attempted to put them into perspective through the use of evolutionary, developmental and neuroscience research.

John Gottlieb