![]() ![]() ![]() I became very fast at this touch based skill, as my eyes were on the numbers on paper (there was no visual feedback - just the numbers that were printing on the tape, but you didn't look at that. Index finger was for the left column, next two for adjacent ones. The keyboard layout was identical to present computer layouts as well present digital calculators. ![]() In the early sixties I took a year out of university and got a job in the internal audit department at the head office of a large insurance company in Toronto.Ī substantial part of my job involved using an electromechanical calculator to check figures submitted by various departments. This might be the reason that the more natural ordering is used, since there's no reason to complicate. Since phone numbers have a fixed number of digits which randomly scattered, the Benford's law doesn't apply here, which means all the digits occur with similar frequencies. This is why the zero key is especially large. Therefore it's sensible to put digits 1, 2, and 3 to the bottom row, as it's closer to the enter and also user reaches them easier.Īs pointed out in the comments, 0 tends to occur very frequently as well, due to rounding using the decimal number system. The graph is something like this and shows heavy bias against the digit "1". It says, that digits 1,2,3 occur more often than 7,8,9 when dealing with random, arbitrarily big numbers, which numbers that users type into calculators, in fact, are. You probably have heard of the Benford's law, also known as the "First digit law". Since I come from mathematics background, this is the first thing that comes to mind. However, records of AT&T Labs' research clearly invalidate it. There's also a theory that phone engineers wanted to slow down people who were fast at entering numerical data, which would jam lines and produce dialing errors, so they reversed the layout. Still, when it came time to place a numeric keypad on a computer keyboard, the calculator model with 7-8-9 at the top prevailed. It turns out that decision was largely arbitrary: no one had done any research about which layout was most convenient for users. When Bell Labs began exploring keypad layouts in the late 1950s they contacted all of the leading calculator manufacturers to find out why they had chosen to put low numbers at the bottom and high numbers at the top rather than the other way around.It is common practice today to use the telephone-keypad layout when designing new products that utilize a keypad, such as Automated Teller Machines.Back then, the industry-standard typical calculator had nine columns of numbers, with 10 numbers in a column, the lowest digits at the bottom, starting with 0 and moving up to 9, and was basically a mechanical adding machine that closely resembled a cash register.By the time when the touch-tone telephone was being designed in the late 1950s, the calculator and adding-machine designers had already established a layout that had 7, 8 and 9 across the top row.Touch-tone key pad was designed to mimic the rotary dial with the "1" on top and the 7-8-9 on the bottom, and AT&T conducted user testing to confirm that this configuration helped eliminate dialing errors.These findings suggest that the preferable keypad layout differs between different age groups and between male and female participants.There's this humongous article called Keyboard Trivia that has collected many of the theories and stories. In the elderly participants, miskeying frequently occurred at dial keys of specific numbers. However, for the female participants, with shorter thumbs, the increase in V-pitch did not improve operability. Results concerning subjective overall usability showed the lowest scores for a V-Pitch of 7 mm and a B-Margin of 5 mm in most groups. Keypads designed by using the L9 orthogonal array differed in vertical pitch (V-Pitch: 7, 8, 9 mm) between keys, horizontal pitch (H-Pitch: 10, 11, 12 mm) between keys, the margin below the bottom row of keys (B-Margin: 5, 13, 21 mm), and phone body width (P-Width: 38, 41, 44 mm). Eighteen young participants (9 males and 9 females) and 12 elderly participants (6 males and 6 females) operated 9 different keypads modeled after commercially available cordless handsets. The present study investigated the effect of keypad layout on the ease of operating small cell phones with the thumb in one-handed operations by young and elderly male and female participants. ![]()
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