So a major challengefor future research is to investigate the use of task analysis techniques in context, assessing theefficiency and effectiveness of these techniques for particular tasks, situations, design problems and organizational structures

Empirical evidence is crucial here, but this research is still nascent, as many techniques have been proposed with littleempirical evaluation.

Usability engineers already rely on simple techniques such as cognitive walkthroughs andheuristic evaluation,but these approaches sacrifice the richness of true task analysis

toolittle is beingsaid about the use of cognitive task analysis products in discussions of cognitive task analysis

For task analysis to realize itspotential, researchers must improve its usabilityand degree ofintegration.

HCI research has evolvedover the past fifty years from focusingon technical (ergonomic) aspects, to conceptual (information-processing) models, towork-process (contextual) models (Kuutti and Bannon, 1991; Grudin, 1990).

Activity theory anticipates and can help to model contemporary ecological approaches to cognitive psychology, such asdistributed cognition(Hollan et al., 2000)

ctivities are not seen in isolation. They are under continuous development, so their historyaccumulates and serves to inform their evolution. This is possible because of the presence of artifacts. Artifacts carry culturein the form of “historical residue,” delivering the lessonsof the past to the future, mediatingbetween different elements of an activity, and enabling the coordinationof complex actions.

Compared toHTA or cognitive modeling,CTA has increasedunderstanding of many important cognitive aspects ofmodern task environments. However, it is unclear how effective CTA techniques are in representing these aspects in a systematic and usefulway (Shepherd, 2001).

CTA requires “making explicit theimplicit knowledge and cognitive-processing requirements ofjobs” (Dubois and Shalin, 2000:42)

GOMS analysis produces a descriptionof a task, often in the form of a hierarchical plan similar to those produced byHTA. However,while HTA generally describes high-level activity, GOMS typically works at the keystroke level. This low-levelfocus arises fromthe requirement that the lowest-level operators in a taskhaverigorousestimates of execution time.

HTA recognizes the responsibility of the operator (user) to planthe use of available resources to attain a given goal, but ittreats the operator’s cognitive processes as a black box: “howbehavior is actually organized is a question for cognitive psychology” (Shepherd 2001:16).

The strengths and weaknesses of HTA flow from its strong system-centric stance

HTAbreaks tasks into subtasks and operationsor actions

Task analysis nowincludes a range of techniques aimed at obtaining descriptions of what people do, representing those descriptions, predictingdifficulties, and evaluatingsystems against functional requirements(Jordan, 1998)

failed to fully integrate technology with user needs to improve the tasks being performed

analyzing the movement of individuals or material, theinteraction between human and machine, and body movement

oncluded that performance was influencedmore strongly by the attention givento workers during the studies thanbyenvironmental effects such as lighting