Average digit span

The middle of both ranges is about seven, which is why the rule is remembered as seven plus or minus two. The ends are not limits. Some people hold more and some fewer, and the same person holds more on a good day than on a bad one. In the computer study the digits were spoken, and testing began at five digits, so the narrower range also reflects how that test was run.

In a digit span task you see or hear a string of digits, one at a time, and then repeat them in order. The longest string you get right is your span. It tells you how much you can keep in mind for a few seconds while you work with it, which psychologists call short-term or working memory.

It does not tell you how well you remember your own life, a language or the things you have studied for years. Those use other kinds of memory, and a short span is no sign that they are weak.

The review gathered many experiments and noticed that people hold about the same number of items however different the items were. Its point was that we hold about seven chunks, and a chunk can be one digit or a familiar group of digits, such as a year or the start of a phone number.

Because the figure is a summary of other people's experiments, it depends on how those experiments were run: how fast the digits came, whether people could rehearse them and how a half-right answer was scored. A test that shows digits more slowly, or lets you type without a time limit, gives a different span from one that does not.

• Grouping: reading a long number in groups of two or three digits holds more than reading it as one string.
• Rehearsal: most people say the digits silently as they come, so how quickly you can say them matters, and number names that are long to say are harder to hold.
• Meaning: a group that looks like a date is easier to keep than a random pair.
• Pace and distraction: slower digits are easier, and noise or a tired mind loses them.
• Practice: a few runs usually teach you to group and rehearse better, which raises the span a little without enlarging your memory.

Researchers also measure the span of positions, for example in a task where you tap blocks in the order they lit up. In a computer version of that task, 187 adults aged 18 to 82 repeated 5.2 blocks on average before missing two in a row, with a spread of 1.2^[3]. The squares moved to new places on every try there, so it is a guide for other versions rather than a standard. An older figure for the classic wooden blocks has been published too, but we have not been able to read it in its paper, and this site shows no number it has not read in its source.

A pattern span counts the squares of a pattern you can hold at a glance. In a small open study of a pattern test on a screen, 40 young adults took part, and those who did it without a second task recalled patterns of 9.3 squares on average^[4]; the visual memory test sets your longest pattern beside that as a mark. In the chimpanzee study behind the chimp test, 9 students got all of five briefly shown numbers right in about 38% of rounds, and the young chimpanzee Ayumu in about 79%^[5].

The sequence memory test places your block span roughly beside those adults, in one of five zones, and the number memory test draws the digit range beside your span. Neither ranks you against other visitors, and both keep your earlier results as short ticks, so you can see whether you are moving.

Set your digit span beside the range as a rough mark, and then forget the range and watch yourself. Take the test on a few different days at about the same time, keep to one device, and see where your own results settle. A span of one length on one afternoon says very little.