Thomas And Chess: Temperament Type Longitudinal Study And Findings

Updated December 7, 2022 by BetterHelp Editorial Team

Temperament can shape how we behave, learn, and interact with other people. In the late 1950s, psychologists Alexander Thomas and Stella Chess launched a 30-year longitudinal study that tried to figure out a child's temperament, with interesting results.

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The New York Longitudinal Study (NYLS)

The New York Longitudinal Study found that nine traits influenced temperament. Each trait had a range of intensity, and the strength of the traits combined to create the child’s unique temperament. By knowing the child’s temperament, parents and caregivers could gauge how the child would react in certain situations and plan for purposeful activities to create a constructive environment for the child. Each of these nine traits was measurable, and extremes at either end of the spectrum were rare. The traits used in the NYLS were:

  • Activity (energetic vs. sedentary): This trait measured how much natural energy a child has. Too little energy makes it harder for a child to complete tasks, but too much energy can make the child harder to control, and they may be unable to sit still for too long, squirming or wanting to get out of their seat at school.

  • Regularity (predictable vs. variable): In life, routines are important, but in the context of this study, routine refers to a child’s natural patterns and schedules for biological functions, like eating, sleeping, and using the bathroom.

  • Initial reaction (open vs. hesitant): When a child faces a new experience, such as a new person, environment, or toy, some accept it quickly, while others withdraw.

  • Adaptability (accommodating vs. resistant): When something in the environment changes, some children adapt quickly, while others struggle. New rules, a new school, or moving to a new house can make a child more reserved or shy, but their environment may too easily influence a child who is too adaptable.

  • Intensity (exuberant vs. lethargic): An exuberant child responds emotionally to stimuli. If a sad event happens, they will cry quite a bit. If something funny happens, they will laugh a lot. But having too big of a response can make it difficult for others to handle those responses. A child with fewer or muted responses may be more challenging for others to read.
  • Mood (positive vs. negative): Some children are naturally more upbeat, but too much positivity can make it difficult for others to know when the child is in distress. A child with a tendency toward negativity can also be hard to read.
  • Distractibility (attentive vs. sidetracked): Children who are distracted easily can observe the world around them but have difficulty focusing on specific tasks. Children who aren't easily distracted can get their tasks done faster but may not notice things around them that can affect them if they don't react in time.
  • Persistence – Attention Span (immersed vs. disinterested): Persistent children can finish a task even if frustrated. If they do homework and encounter a challenging problem, they are less likely to become annoyed and quit. If a child is disinterested, they may quit at the first sign of trouble. Too much persistence can be a problem, too, if a child doesn't realize when they are in over their head.
  • Sensory Threshold (unaffected vs. irritated): This trait relates to sensory stimuli, or how the child responds to touch, brightness, texture, aroma, taste, etc. Children with a high threshold may appear unaffected and are more comfortable with increased stimuli. Those with a low threshold may be bothered or agitated.

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Looking at these results, you may have noticed that these three personalities only make up 65%. The remaining 35% had a combination of traits that didn’t fit neatly into these three personality types. They may be easy sometimes but difficult at other times. As it turns out, children can be quite different from each other based on the traits they were born with.

Why Does Temperament Matter?

Knowing a child's temperament can give you a better understanding of your child and yourself. It's possible to observe very different temperaments even in children in the same family. Between 20 and 60% of temperament is inborn, but it can be shaped by environment and nurturing.

If you were a difficult child and find that some of the traits you were born with still make your life challenging, or if you’re raising a difficult child yourself, talking to a qualified counselor can help. There is a strong connection between the mental health of children and their parents, and taking care of your mental and emotional well-being can help your family as a whole. 

Online therapy has many benefits for busy or stressed parents. Finding a qualified therapist and attending in-person sessions may feel overwhelming if you feel like you don't have time to shower or load the dishwasher. Working with an online therapist at BetterHelp lets you get the help you need from the comfort of home, and you can message your therapist anytime, even if you’re up in the middle of the night with your difficult child who doesn’t want to sleep.  

Studies show that online cognitive behavioral therapy is just as effective as in-person therapy for treating various conditions, including anxiety, depression, panic disorders, and PTSD. If you need help dealing with the stress of raising a difficult child or find that some of your inborn temperament traits are causing you anxiety, reach out to an online therapist to get the help you need.


The results of the  NYLS by Thomas and Church revealed some interesting things about children’s temperament and personality. If you have a difficult child who is putting strain on your family, talking to an online therapist can help you nurture your own mental health so you can help your child to the best of your ability.

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