This paper describes a metric called "performance efficiency," and its use in cognitive task analysis. This metric provides a means of determining the learning efficiency of instructional conditions. Performance efficiency will be described in the context of recording technologies that are often used in software usability studies. While usability is often considered in the programming of software environments, the "learnability" of these environments is more the concern of instructional designers. The advantages and disadvantages of these types of metrics and methodologies will be discussed in detail. Thus the purpose of this paper is to consider the applications of the "performance efficiency" metric to the design of instructional materials. Introduction Educational researchers have used a medical model to develop instructional materials; that is we hope to design instruction, which is both efficient and effective (Lewis & Barron, 2009). Gagné (1964) was one of the earliest educators to describe these two general categories of dependent variables. He proposed most educators are concerned with (1) "the rate of attainment of some criterion performance" (efficiency) and (2) "the degree of correctness of this performance" (effectiveness) (Gagné, 1964, p.295). It is an underlying theme of this paper that when these variables are applied to the design of instructional materials, we are considering the "learnability" of the instruction. Nielsen (1993) defined usability by developing several subcomponents (learnability, efficiency, memorability, errors, and satisfaction). Soloway, Guzdial, and Hay (1994) called for Norman's "user-centered" design philosophy to be more "learner-centered." Nielsen's (1993) definition of learnability "How easy is it for users to accomplish basic tasks" is a subjective measure of "perceived usability," rather than a more objective measure. However, Nielsen (2001) proposed we should consider the user's opinions and suggestions, but only after actually watching them work with the software. That is we must start by observing learners before considering their perceptions. It's interesting that if we were to look to the international standards organization (ISO) for a definition of usability, we would find that they also chose to use Gagné's variables (ISO 9241-11, 1998). While cognitive load may not seem related to usability, similarities reveal themselves if you consider the measures underlying this theoretical framework. Cognitive load theory is an instructional theory that is concerned with the learnability of instructional materials. This theoretical framework has become quite influential within the field of instructional design (Ozcinar, 2009; Paas, van Gog, & Sweller, 2010). Cognitive load theory is primarily concerned with procedural knowledge, task performances and problem-solving. Cognitive load measures are a combination of subjective data (mental-effort ratings) and performance scores (Tuovinen & Paas, 2004). These measures have been found to be reliable and correlated with error rates (Ayres, 2006) but not all cognitive load theorists agree with the use of subjective measures, and have proposed we consider more direct or objective measures (Brünken, Plass, & Leutner, 2003; Whelan, 2007). This concern has led to the impetus for this paper and the "performance efficiency" metric described in the next couple of sections. This type of research (task analysis) has a rich history and is certainly a metric to be used in cognitive task analysis. Task Analysis Task analysis researchers have used observation or photography/videography as a means of data collection for decades (Clark & Estes, 1996; Gilbreth & Gilbreth, 1917). Some of the earliest task analysis studies were made with stopwatches and the newly developed technology of chronocyclegraphy (Gilbreth & Gilbreth, 1917). This was the use of long exposure photography, which allowed for the detection of movements over time. While the Gilbreths were early pioneers of time motion studies, even they were aware of the underlying rationale for this type of research. They state it when they say "that the learner shall be taught the best way immediately, that is, from the beginning of his practice" (Gilbreth & Gilbreth, 1917, p.82). So they were amongst the first to promote efficient instruction, for it allows a learner to be more efficient with their time, and simply learn more.