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Learn about me & my missionApril 10th, 2010 | On Seminal Numbers in Psychology.
This text was fully written by a human.
- I’m exploring the role of numbers in psychology, a topic that hasn’t been widely covered. My goal is to spark curiosity about how specific constants apply to human behavior.
- Miller’s Number (7 ± 2) indicates the limit of information we can hold in short-term memory. This includes tasks such as recalling a series of colors or digits. This number often proves accurate for most people, though individual recall can vary. According to Miller (1956), human short-term memory capacity is consistently limited to about seven items, plus or minus two. This limit holds across a range of information types.
- Dunbar’s Number (150) represents the maximum number of social relationships we can maintain. This concept seems to still hold true even within the context of modern social networks. According to Dunbar (1992), this cognitive limit on stable social-group size derives from a consistent relationship. Specifically, it relates to primate neocortex size and observed group size. The Strel Number (66) refers to the average time it takes to form a habit, derived from repeated daily activities.
What Are the Magic Numbers in Psychology?
Today’s topic is interdisciplinary: numbers in psychology. I’ve never seen an article on this, so I’m creating my own to stir curiosity in others.
Anyone familiar with math probably knows Euler, Bernoulli, Fermat, and high school graduates might recognize Planck, Boltzmann, or Faraday constants.
But not everyone is aware of constants that describe human behavior, derived from empirical psychology and sociology. I’ll share the three most notable ones I’ve encountered; there could be others. Maybe you know some?
Miller’s Number: 7 ± 2 — the limit of information a person can hold in short-term memory. For instance, if shown colors briefly (e.g., 1 second), people can recall about 7 ± 2 colors. The same applies to numbers.
Note: people might see shorter sequences as one item, longer ones as separate digits. When asked for lists like phone numbers, people might remember only parts. Beyond a certain size, it becomes digits while recalling, varying per person.
Interestingly, most people remember exactly 7 (a Gaussian variable, with minimal deviation). However, according to Cowan (2001), a reconsideration of the evidence suggests the true core capacity limit may be closer to 3-5 items. Miller’s higher estimate may instead reflect the use of memory strategies like chunking.
What Are Dunbar’s and the Habit-Formation Numbers?
Dunbar’s Number: 150 — the estimated maximum number of social relationships one can maintain.
Based on studies of tribes and early communities, it still applies to modern social networks. I noticed this when my Facebook friends surpassed 200—I was overwhelmed by the constant news feed. By hiding less relevant connections, I ended up with about 120-130, aligning with those I truly interact with.
How Many Days Does a Habit Take?
Strel Number: 66 — the average number of days to form a habit. Its exact meaning is unclear. However, it seems that repeating an activity daily for this duration helps it become a habit.
According to Lally, van Jaarsveld, Potts and Wardle (2010), the actual time to form a habit varied widely among participants. This range spanned from 18 to 254 days, with 66 days representing only the average. Named after Martin Strel, who spent this time exploring Amazon.com.
Please cite as:
Bielczyk, N.
(April 10th, 2010). On Seminal Numbers in Psychology. Retrieved from: https://nataliabielczyk.com/on-seminal-numbers-in-psychology/
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