Keystroke-level model: Difference between revisions

Revision as of 22:13, 2 June 2023

Revision as of 23:37, 3 August 2023

Line 4:

The keystroke-level model consists of six operators: the first four are physical motor operators followed by one mental operator and one system response operator:<ref>{{cite journal|last1=Card|first1=Stuart K|last2=Moran|first2=Thomas P|last3=Newell|first3=Allen|title=The keystroke-level model for user performance time with interactive systems|journal=Communications of the ACM|date=1980|volume=23|issue=7|pages=398–400|doi=10.1145/358886.358895|s2cid=5918086|ref=5|doi-access=free}}</ref>

* '''K''' (keystroke or button press): it is the most frequent operator and means keys and not characters (so e.g. pressing SHIFT is a separate K operation). The time for this operator depends on the motor skills of the user and is determined by one-minute typing tests, where the total test time is divided by the total number of non-error keystrokes.

* '''P''' (pointing to a target on a display with a mouse): this time differs depending on the distance to the target and the size of the target,<ref>{{cite journal|last1=Fitts|first1=Paul M|title=The information capacity of the human motor system in controlling the amplitude of movement|journal=Journal of Experimental Psychology: General|date=1992|volume=47|issue=3|doi=10.1037/h0055392|ref=3|pmid=13174710|pages=381–91|s2cid=501599 }}</ref> but is held constant. A mouse click is not contained and counts as a separate K operation.

* '''H''' (homing the hand(s) on the keyboard or other device): This includes movement between any two devices as well as the fine positioning of the hand.

* '''D''' (drawing (manually) n_D straight-line segments with a total length of D(n_D, l_D) cm): where n_D is the number of the line segments drawn and l_D is the total length of the line segments. This operator is very specialized because it is restricted to the mouse and the drawing system has to constrain the cursor to a .56&nbsp;cm grid.

Line 135:

While the existing KLM applies to desktop applications, the model might not fulfill the range of mobile tasks,<ref>{{cite book|last1=Li|first1=Hui|last2=Liu|first2=Ying|last3=Liu|first3=Jun|last4=Wang|first4=Xia|last5=Li|first5=Yujiang|last6=Rau|first6=Pei-Luen Patrick|title=Extended KLM for mobile phone interaction: a user study result|journal=CHI EA '10 CHI '10 Extended Abstracts on Human Factors in Computing Systems|date=2010|publisher=ACM|___location=New York|isbn=978-1-60558-930-5}}</ref> or as Dunlop and Cross <ref>{{cite journal|last1=Dunlop|first1=M.|last2=Crossan|first2=A.|title=Predictive Text Entry Methods for Mobile Phones|journal=Personal Technologies|date=2000|volume=4|issue=2–3|pages=134–143|doi=10.1007/BF01324120|s2cid=194691|url=https://strathprints.strath.ac.uk/2580/6/strathprints002580.pdf}}</ref> declaimed KLM is no longer precise for mobile devices. There are various efforts to extend the KLM regarding the use for mobile phones or touch devices. One of the significant contributions to this field is done by Holleis, who retained existing operators while revisiting the timing specifications. Furthermore, he introduced new operators: Distraction (X), Gesture (G), Initial Act (I).

While Li and Holleis <ref>{{cite book|last1=Holleis|first1=P.|last2=Otto|first2=F.|last3=Hussmann|first3=H.|last4=Schmidt|first4=A.|title=Keystroke-level model for advanced mobile phone interaction|journal=CHI '07: Proceedings of the SIGCHI Conference on Human Factors in Computing Systems |chapter=Keystroke-level model for advanced mobile phone interaction |pages=15051505–1514|date=2007|doi=10.1145/1240624.1240851|isbn=9781595935939|citeseerx=10.1.1.192.2364|s2cid=2011796}}</ref> both agree that the KLM model can be applied to predict task times on mobile devices, Li suggests further modifications to the model, by introducing a new concept called operator blocks. These are defined as "the sequence of operators that can be used with high repeatability by analyst of the extended KLM.”.<ref>{{cite book|last1=Li|first1=Hui|last2=Liu|first2=Ying|last3=Liu|first3=Jun|last4=Wang|first4=Xia|last5=Li|first5=Yujiang|last6=Rau|first6=Pei-Luen Patrick|title=Extended KLM for mobile phone interaction: a user study result|journal=CHI EA '10 CHI '10 Extended Abstracts on Human Factors in Computing Systems|date=2010|publisher=ACM|___location=New York|isbn=978-1-60558-930-5|page=3521}}</ref> He also discards old operators and defines 5 new mental operators and 9 new physical operators, while 4 of the physical operators focus on pen-based operations.

Rice and Lartigue <ref>{{cite book|last1=Rice|first1=A.D.|last2=Lartigue|first2=J. W.|title=Touch-Level Model ( TLM ): Evolving KLM-GOMS for Touchscreen and Mobile Devices Categories and Subject Descriptors|journal=ACM SE '14 Proceedings of the 2014 ACM Southeast Regional Conference Article|chapter=Touch-level model No.(TLM) 53|pages=1–6|date=2014|doi=10.1145/2638404.2638532|isbn=9781450329231|s2cid=25139034}}</ref> suggest numerous operators for touch devices together with updating existing operators naming the model TLM (Touch Level Model).

They retain the operators Keystroke (K/B), Homing (H), Mental (M) and Response Time (R(t)) and suggest new touch specific operators partly based on Holleis’ suggested operators: