RE: Size of a clickable area and the WCAG 2 guidelines

In October 2001, Nielsen Norman Group released a study called "Beyond ALT Text: Making the Web Easy to Use for Users with Disabilities". One of their findings/recommendations was: "Avoid very small buttons and tiny text for links", noting that in their usability study, users with low vision and physical disabilities had significant difficulty with small buttons/links. Unfortunately, they did not define "small" or "tiny" or recommend a minimum size.

For the Illinois accessibility standards (http://www.dhs.state.il.us/iitaa), we tried to develop a specific recommendation, somewhat arbitrarily arriving at 16 x 16 pixels for images and 4 or more characters for text (based on size of the smallest icons used in the typical operating systems at that time).
In doing usability studies, we do see users struggle with small buttons/links, especially radio buttons (without labels) and single-letter links (e.g., in an alphabetical index). It would definitely be useful to have an uniform standard for minimum clickable areas.

Mike

________________________________________
From: Jonathan Avila [jon.avila@ssbbartgroup.com]
Sent: Wednesday, February 24, 2010 8:04 AM
To: w3c-wai-ig@w3.org
Subject: RE: Size of a clickable area and the WCAG 2 guidelines

What I guess most likely happened is that 1. As Jim Tobias said there was
not as large of a political effort to push for stronger mobility
guidelines and 2. Perhaps there was not an exact technical specification
that would support the majority of users with mobility impairments -- I
understand Fitts law provides some guidance in this area.  In order to
require something you really need a proven and quantitatively researched
algorithm for achieving the desired results for the population in need.

Jonathan

Received on Wednesday, 3 March 2010 19:50:33 UTC