Psychologists use personality traits such as extroversion, neuroticism or anxiety as a means of characterizing typical patterns of thought, emotion and behavior that differ from one person to the next. From this perspective, the constituents of personality consist of a collection of relatively stable traits that are hard to change.
But the assumption that you can routinely measure these traits using questionnaires that identify typical behavior has come into question in the past two decades. It is not only that behavioral changes happen often but that they occur from day to day and hour to hour. Someone could be open and agreeable at noon but negative and rigid at two o’clock. Such oscillations in daily feelings and behavior—designated with the bland title of intraindividual variability, or IIV—are, in fact, so great that they rival or even exceed the differences in personality traits such as extroversion or conscientiousness that can be measured between one person and another.
The name for this new field appeared in 2004 when Peter C. M. Molenaar, an emeritus professor of human development and psychology at Pennsylvania State University, championed IIV in a manifesto entitled “Bringing the Person Back into Scientific Psychology, This Time Forever.” In it, he used a series of math and physics calculations to illustrate the degree of dynamic flux in personality while deriding standard methods of psychological testing.
This view of the importance of IIV has continued to gain popularity in the years since publication of Molenaar’s manifesto. It has contributed to a better understanding of personality and led to changes in some forms of psychotherapy. Researchers have learned that variability in responding to stressful daily events—from having a fight with your spouse to getting stuck in traffic—can yield important insights about people’s long-term emotional and physical health.
The research underlying this shift can be seen in a 20-year study of stress and health that also probed daily personality variability in more than 3,500 adults. Penn State developmental psychologist David Almeida and his colleagues asked subjects on eight consecutive days about stress levels and emotions throughout the previous 24 hours (and gathered a series of physiological measures). The list of people’s stressors included arguments with a family member, work deadlines, an overload of home tasks and a retinue of ordinary daily hassles. Among the many emotions the researchers asked about were joy, anger, fear and anxiety. They also made queries about thoughts related to worry and behaviors such as physical activity and sleep. The investigators repeated this probe twice more at 10-year intervals. Almeida says that they concluded that “daily experience—once deemed relatively unimportant to health—has both short- and long-term consequences on a variety of emotional, physical and cognitive outcomes.”
Almeida’s team calculated how much of what we typically think of as a personality trait actually is just that or can be understood as a passing emotion. “We see it in how grumpy people are,” he says. “We think, ‘Oh, this is a grumpy person.’ In fact, half of their grumpiness is a personality trait, and half would be within the person’s variability from day to day.” He notes that people with positive traits such as openness or agreeability show only a 30 percent variation in traits such as quickness to anger or worry.
Some researchers have delved further in trying to determine how much one’s immediate circumstances affect short-term psychological states. Stanford University professor of psychology and communication Nilam Ram has focused his work on how these hour-to-hour, day-to-day fluctuations are a response to the context in which they occur—such as at work, at home, while spending time with one’s children or at the doctor’s office. Until recently, high or low emotional variability had been seen as a personality trait in itself. Ram says, however, that these ups and downs can reflect the coming and going throughout the day of different aspects of an individual’s personality or an immediate response to a person or event.
Take, for example, an individual participating in a study that gathers hourly reports of their emotions. Someone with high IIV might be considered an emotionally labile person. Or their emotional fluctuations might indicate that they are experiencing a series of unpredictable events in their life, perhaps arising from a chaotic workplace. In fact, Ram says, the emotional reports researchers receive from people they observe in their studies are probably a combination of some aspects of the immediate environment and elements of their personality—how reactive they are to what’s around them and how well they regulate their emotions.
Stress in the moment differs depending on the kind of pressures exerted. Scientists have learned to measure and evaluate the impact of certain categories of stress. A fight with a spouse often results in more of an emotional upset than a work deadline, which, in turn, applies more pressure than daily hassles such as train delays or finding out the dog has pooped on the rug again.
While researchers typically measure IIV by assessing the same person at short intervals—such as every 24 hours for a week or five times each day—psychologist Nadin Beckmann of Durham University in England and her colleagues adopted a different approach. The investigators asked each of the 288 working professionals in their study a series of questions about their personality—whether they were hardworking, contemplative, vulnerable, moody, and so on—at just one point in time and presented the same queries to up to five of each of the participants’ family members, close friends or colleagues.
Momentary states, Beckmann explains, reflect how particular personality traits reveal themselves as a person responds to differing situations. We know intuitively that we do not think, feel and behave the same way at home as we do at work or while out socializing with friends. Beckmann’s results show that intrapersonal variability fluctuates systematically by context regardless of which person is evaluating it. A person might be seen as more conscientious at work than at home and more extroverted with friends than with co-workers.
As researchers have learned to quantify this kind of hour-to-hour variability, they have started to evaluate what vicissitudes mean in devising a larger picture of personality. Ram says he might measure hourly fluctuations in a person’s mood against monthly variations in self-esteem. If the person’s mood changes a lot but their self-esteem remains relatively constant, one interpretation might be that their level of self-esteem is not much influenced by the temporary highs or lows they might experience from a compliment or a put-down.
In recent years Penn State research psychologist and cognitive-behavioral therapist Michelle Newman has found IIV invaluable both for performing research and for devising new ways to treat patients. In the days before smartphones, she says, patients in therapy or participants in a study would fill out a questionnaire that summarized their beliefs about themselves. They were asked to record hour-to-hour feelings with pen and paper or on an electronic note-taking device such as a PalmPilot. Finding these tasks cumbersome, they’d wait until the end of the day to record their thoughts and feelings. The resulting data? “Worthless!” Newman says.
By creating specialized apps for smartphones, psychologists have been able to monitor people’s emotions and experiences several times a day and reap more nuanced reflections of their psychological state. In researching fluctuations in people with generalized anxiety disorder (GAD), Newman has used this minute documentation of their thoughts and feelings to challenge previous beliefs among some psychologists about the cause of the incessant worry that is the primary symptom of GAD. Earlier theories that were based on people’s summaries of their feelings posited that individuals worry in order to mute negative feelings.
Newman’s research suggests the opposite: incessant worry acts to sustain negative emotions. In one study, she and her colleagues monitored 83 people with GAD over eight days just before or right after a social interaction that lasted a minute or more. On average, the scientists found that people with GAD generally felt better after these social interactions, which suggests that the encounters were likely pleasant or at least benign. Counterintuitively, she found that those who worried less before the social encounter had more feelings such as anxiety and sadness after it. Those who worried more before the encounter felt happier or more contented afterward.
This study confirmed Newman’s theory that anxious people believe that if they worry about a bad outcome (no matter how unlikely it is to occur), they won’t experience the gut punch of something awful happening to them after they let themselves feel happy and optimistic. When a bad thing doesn’t happen, she says, they feel relief, which reinforces their belief that worry protects them. Without these detailed logs of fluctuations in thoughts and feelings throughout the day, the study would have missed such insights.
Data gathered at frequent intervals also help therapists shape treatments adapted to individual patients. Many people don’t know or may not remember what triggers their anxiety, but therapists can ferret this out by linking higher anxiety levels to in-the-moment events. They can prompt a patient to employ specific strategies learned previously in therapy to counter their worry. For example, using a technique called cognitive restructuring, patients might compare things that they worry might happen with real events to help them realize their worries are baseless.
Anxious people don’t have only negative feelings, but they tend to minimize the positive ones. “We don’t just want to lower negative feelings,” Newman says. “We also need to enhance positive feelings.”
To reinforce these good feelings, Newman’s colleague, Skidmore College psychologist Lucas LaFreniere, created a phone app called SkillJoy. Several times a day at random intervals, the app prompts anxious people to focus on an enjoyable thing in the present moment—such as seeing a friend, making someone laugh or hearing a great song—and to really “savor” what they are contemplating for a minute or two. A recent study found that after seven days, SkillJoy users worried less than they did before using the app.
This understanding of emotional flux throughout the course of the day has led researchers to ask whether a high level of IIV works for or against people. Newman’s opinion in this debate is clear. “Variability is good,” she says, “and there is no clear answer about when it indicates psychopathology.” Others in the field are less certain. While some studies have linked high variability with neuroticism, others have failed to do so. A lot depends on context. A person with high IIV, Ram says, may be successfully adapting to a tumultuous life, while someone with lower IIV may have a predictable, routinized life and may actually be more rigid.
According to recent studies by scholars such as University of Oklahoma Health Sciences Center researcher Lizbeth Benson, having a greater variety of emotions that range from enthusiasm and determination to sadness and fear—dubbed emodiversity by Jordi Quoidbach, now an associate professor at Esade Law School in Barcelona—is thought to help people better adjust to different situations throughout the day. “The coolest thing we showed is that for those who experienced high levels of negative emotion,” Benson says, those who had more kinds of negative emotions tended to have better health outcomes.
For therapists and patients, acknowledging the highs and lows of daily emotions—some bad, others eminently good, some moods way up, others beyond down—has provided new insights for the enduring goal of psychology to help define who we are so that we can learn to live with that knowledge and find ways to become more the people we want to be.