Model based design NGOMSL and CPM- GOMS

NGOMSL “Natural GOMS Language” Addresses gaps in KLM modelling Formal language with restricted English syntax The benefit of the formal language is that each statement roughly corresponds to a primitive mental chunk, so you can estimate the learning time (total execution time) Addresses gaps in KLM modelling Learning time measured by the # of NGOMS statements It also has statements that represent working memory operations (retain and recall) So the effective use of working memory can be estimated by executing this model

NGOMSL for move text Method for goal: Move text Step 1: Accomplish goal: cut text Step 2: Accomplish goal: paste text Step 3: Return with goal accomplished Method for goal: cut text Step 1: Accomplish goal: Highlight text Step 2: Retain that the command is CUT, and accomplish goal: Issue a command (IC) Method for goal: paste text Step 1: Accomplish goal: Position cursor at insertion point Step 2: Retain that the command is PASTE and accomplish goal: IC

CPM- GOMS Cognitive Perceptual Motor or Critical Path Method is another variant of GOMS Unlike KLM and other models (serial operations) CPM-GOMS model handles parallel operations Ex: Point and shift-click

CPM- GOMS It is more detailed than KLM It tackles the serial assumption of KLM, allowing multiple operators to run at the same time Uses parallel cognitive model Each processor is serial Different processors run in parallel

CPM- GOMS CPM- GOMS have A perceptual processor (PP) A cognitive processor (CP) Multiple motor processors (MP) one for each major muscle system that can act independently For GUI interfaces, the muscles we mainly care about are the two hands and the eyes

The biology of the model Perceptual processor Cognitive processors Motor processors

Critical Path determines time We build a CPM-GOMS for point-shift-click operation

CPM for point-shift-click First, the cognitive processor (CP) which initiates everything decides to move the eyes to the pointing target Next, the eyes actually move (MP eye), but in parallel with that, the CP is deciding to move the mouse The right hand motor processor (MP right) handles it and the time is determined by the fitt’s law While the hand is moving, the PP is in active and perceive both eyes and mouse move have found the target (perceive target and cursor blink)

CPM for point-shift-click Then the CP verify the target and decides to press the shift key This instruction is passes to the left hand motor processor (MP left) MP left press the shift button

CPM GOMS-Critical Path Method Critical path can be found though this graph of overlapping tasks It can be defined as - the path that takes the longest time, since it will determine the total execution time for this method (model) Note that this task would be just P and K in the KLM model This model has minimize the errors (No errors) by parallelizing as much as possible

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