Since most of us were never called on in class to answer a tough time-estimation question, or quizzed on the lengths of tones in milliseconds, we don't have a good grasp of our skill in this area. It's kind of exciting. You could be a prodigy and not know it! But a cold dose of reality comes from new research saying skill in time estimation is tied to mathematical intelligence. If you're not amazing at math, your temporal abilities probably aren't A-plus either.

Writing in PLos ONE, a group of Italian researchers describe a study done on 202 adults. The subjects listened to a series of tones through headphones, and estimated the length of each tone in milliseconds. ("We first made sure that participants knew that one millisecond is a thousandth of a second.") Tones ranged from 100 to 3000 milliseconds long. That's a tenth of a second to three seconds, for those of you who are non-amazing at math.

Everyone became more accurate as tones got longer. Unsurprisingly, it's easier to guess that a sound lasts for one second or three seconds than 100 or 200 milliseconds.

Subjects were also tested on their arithmetic skills, general intelligence, and working memory. All these tests came from a standard set of IQ questions. Arithmetic problems ranged from very simple ("What's 5 apples plus 4 apples?") to more difficult ("If 8 machines can finish a job in 6 days, how many machines are needed to finish it in half a day?"). To gauge non-mathematical intelligence, researchers gave subjects a verbal comprehension test (for example, "How are an orange and a banana similar?"). A challenge to remember strings of digits and recite them forward or backward tested subjects' "working memory," which is the ability to hold things in the mind and process them.

People's accuracy at guessing the length of tones was closely tied to their mathematical IQ. Less accurate estimators had lower math scores, and better estimators were better at math. But this connection didn't extend to general intelligence, or at least not to verbal intelligence: there was no relationship between subjects' estimation skills and their performance on the verbal comprehension test.

The researchers also found no relationship between time estimation and working memory. This is a little unexpected, since judging how long something took seems like a task for the short-term memory. And a previous study of time estimation did find a connection to working memory. But in that study, subjects did arithmetic problems while estimating times. The authors argue that making subjects do two things at once was a test of their working memory to begin with; subjects who excelled at estimating times while doing math problems would necessarily have a good working memory. In the new study, tasks were taken one at a time, and skill at time estimation seemed to be separate from working memory.

Subjects were also asked to rate their own mathematical ability on a scale of 0 to 10. These ratings followed the same pattern as math IQ scores: people who considered themselves as better at math were also better at estimating tone lengths. (Interestingly, out of the 202 Italian subjects, not one person rated himself or herself a 10. Does this indicate a general trepidation toward math? Some sort of cultural modesty? Surely in the U.S. someone would have claimed to be the best.)

Your sense of time, then, seems to be tied not to your intelligence or memory, but to your sense of numbers. The authors believe the connection lies in lines--the timeline and the number line. Previous research has shown that people use a mental number line to do math, sensing smaller numbers to the left and larger numbers to the right. People estimate lengths of time using another left-to-right mental path: small intervals are on the left, and larger intervals are on the right. (How would these experiments play out in a culture that reads right-to-left, or vertically?)

If it's all about lines, then mathematical and temporal skills may come down to a person's ability to judge increments, to arrange items in a path. Working with your mental timeline or number line, that is, may really be a spatial skill. And the best time estimators in the classroom might be the line leaders.

Kramer, P., Bressan, P., & Grassi, M. (2011). Time Estimation Predicts Mathematical Intelligence PLoS ONE, 6 (12) DOI: 10.1371/journal.pone.0028621

Image: James Laing/Flickr