Hick's law Guide, Meaning , Facts, Information and Description

Hick's law, or the Hick-Hyman law, is a model used in human-computer interaction that describes the time it takes for a user to make a decision as a function of the possible choices he or she has. Given n equally probable choices, the average reaction time T required to choose among them is approximately

where b is a constant that can be determined empirically by fitting a line to measured data. According to Card, Moran, and Newell (1983), the +1 is "because there is uncertainty about whether to respond or not, as well as about which response to make." The law can be generalized in the case of choices with unequal probabilities p_i of occurring, to

where H is the information-theoretic entropy of the decision, defined as

Hick's law is similar in form to Fitts' law. Intuitively, one can reason that Hick's law has a logarithmic form because users are able to subdivide the total collection of choices into categories, eliminating, say, half of the remaining choices at each step, rather than considering each and every choice one-by-one, which would require linear time.

Hick's law has been shown to apply in experiments where the user is presented with n buttons, each having a light bulb beside them. One light bulb is randomly lit up, after which the user must press the corresponding button as quickly as possible. Obviously, the decision to be made here is very simple, requiring little conscious thought.

Hick's law is sometimes cited to justify decisions about menu design (e.g. [1]). However, applying the model to menus must be done with care. For example, if a user is given a word (e.g. the name of a command) to find in a list of randomly ordered words (e.g. a menu), the user will have to scan each word in the list, requiring linear time, so Hick's law does not apply. If the list is arranged alphabetically, however, the user will likely be able to use a subdividing strategy that may well require logarithmic time.

Yet another situation is when the user does not know the exact name of the command they seek in a menu, but would likely recognize it if they saw it. In this case, the user may or may not be able to use a subdividing search strategy, depending in part on how menu items are categorized and how well the user can use categories to speed their search.

For considerations of Hick's law and Fitts' law in the context of menu and submenu design, see Landauer and Nachbar (1985).

Table of contents

1 See also 2 References 3 External Links

See also

• The Magical Number Seven, Plus or Minus Two

References

• Original work
  • W. E. Hick. On the rate of gain of information. Quarterly Journal of Experimental Psychology, 4:11-26, 1952.
  • R. Hyman. Stimulus information as a determinant of reaction time. Journal of Experimental Psychology, 45:188-196, 1953.
• Selected subsequent work
  • T. K. Landauer and D. W. Nachbar. Selection from alphabetic and numeric menu trees using a touch screen: Breadth, depth, and width. In Proceedings of ACM CHI 1985 Conference on Human Factors in Computing Systems, pages 73--78, 1985. http://doi.acm.org/10.1145/317456.317470
• Overviews
  • Stuart K. Card, Thomas P. Moran, Allen Newell (1983). The Psychology of Human-Computer Interaction.
  • A. T. Welford. Fundamentals of Skill. Methuen, 1968. Pages 61-65.

External Links

• Usability Glossary: Hick's Law

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