Do Down’s Syndrome Individuals Exhibit the Same Variability in Trait Behavior as Those Who are Developmentally Typical?

42-15641190          About ten years ago, I received an email from a colleague in England. She worked with Down syndrome individuals and had a question for which I had no answer. To wit: do Down’s syndrome individuals (DSIs) display the same degree of variability on personality traits as developmentally typical individuals (DTIs)? She wasn’t asking if the means of these two groups were the same, but rather if the standard deviations were similar. In other words, do DSIs show the same extremes, for example, of extraversion and introversion, of openness and closedness, as do  DTIs. I knew of no research that addressed that question, but I told her that I would let her know if I discovered anything.

          A few years ago, I came upon three colleagues who were interested in the same question: Dr. David Gilmore of the University of North Carolina at Charlotte, Ms. Pat Farmer of the Allegro Foundation, and Ms. Lauren Thomas, at the time a research intern with us here at CentACS and currently a graduate student at the University of Louisville. We decided to take our established personality assessment for adolescents, the SchoolPlace Big Five Profile®, and translate it into a short form that raters could use to rate the Big Five behaviors of Down syndrome individuals. Even though we are still collecting data, a preliminary analysis reveals some interesting results.

               To date, we have 67 sets of data—most are paired, with one family member and one caregiver rating the same Down syndrome individual. While this is a relatively small number, we have been eager to take a look for any patterns that may be emerging. Here is what we found: 


Down Mean(n=67) Typ Dev Mean(n=1,200) Down SD Typ Dev SD
N 23.4 22.1 6.3 4.9 
E 37.4 39.3 8.9 5.8 
O 20.6 24.1 5.07 4.02
A 34.2 31.1 6.6 5.63
C 22.4 32.6 5.4 7.06 

          For definitions of the Big Five supertraits N, E, O, A, and C, see the Big Five Quick Start, an introduction to the Five-Factor Model of personality for human resource professionals, which is located on our website. Although the two assessments (the SchoolPlace Big Five Profile short form and the Disabilities Big Five Profile) that we are comparing here used a slightly different number of items (48 and 52, respectively), I have adjusted the means and standard deviations so as to eliminate the effect of the different lengths. These are my tentative findings:

  • DSIs show a moderately lower mean on O, suggesting that they exhibit a somewhat lower level of creativity, complexity, and comfort with change.
  • DSIs show a dramatically lower mean on C—almost two standard deviations, suggesting they exhibit a noticeably lower preference for perfectionism, focus, ambition, concentration, and methodicalness—generally more contented with the way things are.
  • DSIs show a moderately higher mean on A, suggesting that they exhibit a somewhat stronger tendency to defer to others and be comfortable in the background.
  • The means on N and E show no difference between the DSIs and the DTIs, suggesting that levels of happiness (positive emotions dominating negative emotions) are similar.
  • The standard deviations for N, E, O, and A are higher among DSIs, suggesting that there is more variability in these four areas than is found among DTIs—more extremes in behavior. More extremely neurotic individuals, and more extremely calm ones; more extremely extraverted as well as more extremely introverted; more extremely imaginative and more extremely literal; more who are extremely deferential, and more who are extremely defiant, in comparison to the DTIs.
  • The only supertrait that suggests LESS variability among DSIs is C, suggesting that DSIs as a group show less extremely ambitious behavior, as well as less of the opposite.

          So, the tentative answer to my English colleague is: Down syndrome individuals show as much or more variability in trait behavior as compared to typically developing individuals, with one exception—Conscientiousness/Consolidation/Will to Achieve, where they show not only less variability, but a substantially lower mean.

          Assuming that our continuing data collection supports these trends, clear implications lie in store for working with DSIs. Historically, people have assumed that DSIs were all similar behaviorally—that they all like repetition, were all moderately sociable, and so forth. This data clearly challenges those assumptions. Hence, among DSIs, we need to take individual differences into account with respect to career choices, roles in group homes, managing conflict, teaching/learning style, relationship management, motivational strategies, therapy modes, and, in short, we need to employ the same individual difference sensitivities with DSIs that we use with our developmentally typical friends, family, and associates.

6 thoughts on “Do Down’s Syndrome Individuals Exhibit the Same Variability in Trait Behavior as Those Who are Developmentally Typical?

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  1. Wow! That is very interesting and gives us data to debunk the “they’re always so happy” myth. Thank you for doing this. I look forward to further information.

  2. Depending on the age of children/adults tested, this result (of people with DS having less of a will to achieve) is probably a society-induced resignation or hopelessness. I am well acquainted with several teens with Down syndrome (my fifteen-year old daughter and her friends), and they all have a very healthy will to succeed in life. People with Down syndrome have a mental impairment. In NO way does this affect their temperment (forget the stereotype of the easy-going kid with DS)/personality/ ambitions. However, stupid people around them who pamper them, stereotype them, etc., DO sometimes affect their ability to see themselves as possible achievers (on their own level).

  3. “show less extremely ambitious behavior, as well as less of the opposite.” I am not sure I understand what this means…less extremely unambitious behavior… meaning some are extremely ambitious?

  4. Two things are meant here: the overall average score for Down syndrome individuals is lower than that for typically developing individuals, AND and standard deviation is smaller. That means that the average achievement is somewhat lower, and that, as a group, Down syndrome individuals are clustered closer to the average, with fewer extreme scorers at both ends of the distribution. Another way of saying it is that DSIs are more homogeneous with respect to ambition, with proportionately fewer extremely ambitious individuals, as well as fewer individuals with little or no ambition. Clearer?

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