David, I was too laconic in my previous message and did not explain what meaning of %u201Cinterference%u201D was used.
Webpage scrolling is an automatic activity involving perceptual and motor skills working in concert. This automatic activity is unconscious and effective. A portion of user%u2019s cognitive load allocated to scrolling is very low. In other words, the user do not %u201Cthink%u201D about how to scroll a page, he simply scrolls it, and it scrolls. When you place second scrolling mechanism (slider) on a webpage, you introduce a dissonance into automatic scrolling activity. Now for the same task %u2013 scrolling %u2013 there are two modes of operation: one for the scrollbar, another for the slider. (Slider cannot be operated by a mouse wheel; it is not clear how to scroll down exactly by one page etc.) As a result, a user is faced with two different scrolling controls and his automatic skill became damaged. Unconscious became conscious: the user starts thinking about how to act in each case. This is what I meant by %u201Cinterference%u201D, a cognitive interference. Then, imagine a realistic situation when at the current moment of page scrolling only a half of the slider is visible on screen while its another part is hidden below the bottom edge of the browser window. This is a real dilemma for a user: which of two scrolling mechanisms to use: scrollbar or slider?.. Finally, I do not think the concrete example of a slider you mentioned in your initial message is very different visually from a scrollbar. Mentally rotate that slider by 90 degree right and imagine that current webpage is long and therefore its scrollbox is small: in this case a slider and a scrollbar will look as twins%u2026 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Posted from the new ixda.org http://www.ixda.org/discuss?post=42001 ________________________________________________________________ Welcome to the Interaction Design Association (IxDA)! To post to this list ....... [email protected] Unsubscribe ................ http://www.ixda.org/unsubscribe List Guidelines ............ http://www.ixda.org/guidelines List Help .................. http://www.ixda.org/help
