User Models and Models of Human Performance Essay

User Models and Models of Human Performance - Essay Example There are seven steps that are involved in developing a critical path model (Stanton 2007). The first is defining the tasks. In a situation where a driver is driving a car on the road and his mobile phone rings, the river will perform the following tasks: The second step identifies the input and output sensory modalities used in the tasks. For example, in retrieving the mobile, the driver will use his left or right hand, making the task step manual. Pressing buttons is also manual and can either be done by the right or the left thumb. Talking on the phone constitutes speech modality whereas listening requires auditory. Reading the screen requires visual modality and responding can involve cognitive modality. Step 3 of the approach requires construction of a chart, where dependency of the tasks is assessed (Sikora & Hattan 2009). The tasks need to be followed in a specific order, one after the other, and two tasks having the same modality need to be performed in series. Step 4 involves assigning the task time and these estimates should be accurate, unbiased and consistent (Thornley 2003). For example, retrieving the mobile can take five, six seconds on average, whereas talking can take long, depending on the duration of the conversati on. Pressing the buttons can take up to half a second each, whereas reading and looking at the screen can consume two to three seconds each. Then forward pass time needs to be calculated by adding up the individual times of each task, and, assuming a one minute long conversation, it becomes 73 seconds. Then backward pass is calculated. The last step is the calculation of the critical path, which is done by identifying the nodes which have zero difference between Earliest Start Time and Latest Finish Time. The model will provide a comprehensive procedure to make adjustments for variations in user performances. The arrangement of elements can be evaluated by a cognitive model and the design can be adjusted to outcomes of the