2. Literature Review
2.3. Theories Used in Information Systems (IS) Research
2.3.2 Theory of Planned Behaviour (TPB)
The TPB posits that an individual's behaviour is driven by behavioural intentions where behavioural intentions are a function of an individual's overall attitude toward the behaviour, the overall subjective nonns surrounding the perfonnance of the behaviour, and the individual's perception of the ease with which the behaviour can be perfonned.
(behavioural control).
Overall Attitude and Overall Subjective Nonns are defined as in the TRA above.
Behavioural control is defined as one's perception of the difficulty of perfonning a particular behaviour. The TPB views the control that people have over their behaviour as lying on a continuum from behaviours that are easily perfonned to those requiring considerable effort, resources, etc.
Although Ajzen (1991) has suggested that the link between behaviour and behavioural control outlined in the model should be between behaviour and actual behavioural control rather than perceived behavioural control, the difficulty of assessing actual control has led to the use of perceived control as a proxy.
The following is a diagrammatic representation of the "Theory of Planned Behaviour".
Overall
Perceived Behavioural
Control
Figure 2: Theory of Planned Behaviour
Behavioural Intention
Behaviour
Note further that a difference between TRA and TPB includes an interaction between Overall Subjective Norm and Overall Attitude toward act or behaviour as well as Perceived Behavioural Control.
2.3.3 Technology Acceptance Model
The "Technology Acceptance Model" (TAM) is an information systems theory that models how users come to accept and use a technology. The model suggests that when users are presented with a new software package or innovation, a number of factors influence their decision about how and when they will use it, notably:
• "Perceived usefulness" (PU) - This was defined by Fred Davis (1989) as "the degree to which a person believes that using a particular system would enhance his or her job performance".
• "Perceived ease-of-use" (EOU) - Davis (1989) defined this as "the degree to which a person believes that using a particular system would be free from effort".
The technology acceptance model is one of the most influential extensions of Ajzen and Fishbein's theory of reasoned action (TRA) in the literature. It was developed by Fred Davis and Richard Bagozzi (Bagozzi et al., 1992; Davis et al., 1989). The TAM replaces
many of TRA' s attitude measures with the two technology acceptance measures "ease of use", and "usefulness". The TRA and TAM, both of which have strong behavioural elements, assume that when someone forms an intention to act, that they will be free to act without limitation.
In the real world, however, there will be many constraints, such as limited ability, time constraints, environmental or organisational limits, or unconscious habits which will limit the freedom to act (Bagozzi et al., 1992).
The following is a diagrammatic representation of the "Technology Acceptance Model".
Perceived Usefulness
~
Behavioural ActualIntention to system use
/
usePerceived Ease of Use
Figure 3: Technology Acceptance Model
Bagozzi Davis and Warshaw noted:
"Because new technologies such as personal computers are complex and an element of uncertainty exists in the minds of decision makers with respect to the successful adoption of them, people form attitudes and intentions toward trying to learn to use the new technology prior to initiating efforts directed at using. Attitudes towards usage and intentions to use may be ill-formed or lacking in conviction or else may occur only after preliminary strivings to learn to use the technology evolve. Thus, actual usage may not be a direct or immediate consequence of such attitudes and intentions. "(Bagozzi et al., 1992)
Earlier research on the diffusion of innovations also suggested a prominent role for perceived ease of use. Tornatzky and Klein (1982) analysed the relationship between the characteristics of an innovation and its adoption, finding that compatibility, relative advantage, and complexity had the most significant relationships with adoption across a broad range of innovation types. Eason (as cited in Stewart, 1986) studied perceived usefulness in terms of a fit between systems, tasks and job profiles, using the terms "task fit" to describe the metric.
Several researchers have replicated Davis's original study (Davis, 1989) to provide empirical evidence on the relationships that exist between usefulness, ease of use and system use (Davis et al. 1989; Hendrickson, Massey & Cronan, 1993; Segars & Grover, 1993; Subramanian 1994; Szajna 1994). Much attention has focused on testing the robustness and validity of the questionnaire instrument used by Davis (ibid). Adams et al.
(1992) replicated the work of Davis (ibid) to demonstrate the validity and reliability of his instrument and his measurement scales. They also extended it to different settings and, using two different samples, they demonstrated the internal consistency and replication reliability of the two scales. Hendrickson et al. (1993) found high reliability and good test-retest reliability. Szajna (1994) found that the instrument had predictive validity for intent to use, self-reported usage and attitude toward use. This research has confirmed the validity of the Davis instrument, and supports its use with different populations of users and different software choices.
Segars and Grover (1993) re-examined Adam's et at. (1992) replication of the Davis's work. They were critical of the measurement model used, and postulated a different model based on three constructs: usefulness, effectiveness, and ease-of-use.
Venkatesh and Davis extended the original T AM model to explain perceived usefulness and usage intentions in terms of social influence and cognitive instrumental processes.
The extended model, referred to as TAM2, was tested and validated in both voluntary and mandatory settings (Venkatesh and Davis, 2000).