These come from a long study that followed children from infancy into adulthood, and the reason they are still quoted seventy years later is that the differences showed up before any parenting had happened.
The groupings
| Group | Roughly | What it looks like day to day |
|---|---|---|
| Easy | 4 in 10 | Regular sleep and appetite, takes new things in stride, mostly positive |
| Slow to warm up | 1.5 in 10 | Hangs back, needs to watch before joining, warms up given time and no pushing |
| Difficult | 1 in 10 | Intense, irregular, reacts hard to change and to being interrupted |
| Mixed | 3.5 in 10 | Some of each, in no clean pattern |
The largest group is the one nobody names, which is worth knowing before deciding your child is a type.
The nine things underneath
The groups are a summary of nine separate traits: activity level, regularity, first reaction to something new, how fast they adapt, how intense their reactions are, general mood, how easily distracted, how long they persist, and how sensitive they are to noise, texture and light. A child can be extreme on two of those and unremarkable on the rest.
Why it is worth knowing
Not as a label. It is worth knowing because the mismatch between a child's temperament and what a house or a classroom expects is where most of the trouble actually lives. A slow-to-warm child in a family that values plunging in gets read as difficult. The same child somewhere patient is unremarkable.
Practically it changes what goes on a chart. A child who reacts hard to change should be earning something for transitions, because for them that is the difficult thing, and putting the easy stuff on a chart for a child whose hard thing is elsewhere is how a chart ends up measuring nothing.