Date of Degree


Document Type


Degree Name





Marios Koufaris

Subject Categories

Advertising and Promotion Management | Business | Marketing


Attitudes; Flexibility of Multi-Device Use; Mental Workload; Multi-Device Use; Task Performance; Task-Technology Fit Theory


Given the widespread use of multiple devices (such as desktop computers, smartphones, and tablets) in performing a task, systematic, theoretic, and empirical studies pertaining to motivations regarding, performance outcomes, and attitudes toward multi-device use have become essential. Despite the increasing importance of multi-device use, research remains scarce regarding this topic.

To comprehensively understand the issues of multi-device use, this dissertation comprises three complementary studies, each of which focuses on a different aspect of multi-device use: Given the availability of multiple devices, what are the motivations behind multi-device use as opposed to the use of only one device to complete a set of related tasks (antecedents; Study 1)? How do people use multiple devices to lead to better performance than when using a single device (performance outcomes; Study 2)? How do users feel about multi-device use when they are free or forced to switch from using one device to another to complete a task (psychological processes; Study 3)?

Drawing on task'technology fit theory and mental workload, this dissertation presents two research models for Study 1 and Study 2, in order to gain deep insight into what happens before (i.e., motivations) and after multi-device use (i.e., task performance). Moreover, on the basis of task'technology fit theory and psychological reactance theory, this dissertation presents a research model for Study 3 to understand the impact of flexibility of multi-device use on users' attitudes. A survey, video recording, and experiments were conducted to collect data for Study 1, 2, and 3, respectively. Partial least squares were used to analyze research models of Studies 1, 2, and 3.

Our empirical findings of Study 1 indicate that perceived task fit with multi-device use is a critical factor that forms users' attitudes toward and expected satisfaction with multi-device use, both of which trigger their intentions to use multiple devices. However, unfamiliarity with multi-device use increases perceived complexity of multi-device use. Such complexity hinders users from perceiving good task fit with multi-device use. The results of Study 2 show that when users can select the right device from their device portfolios to deal with a certain subtask, the task can be completed more quickly and accurately. They also indicate that increasing the number of device switches generates a higher number of application switches and physical movements, both of which add time to task completion. The results of Study 3 indicate the existence of psychological reactance (i.e., as assertive affective and cognitive reactions to a threatened or eliminated freedom) in the context of non-flexibility of multi-device use. This reactance negatively influences affective and cognitive appraisals and in turn affects users' satisfaction with multi-device use and continued intention toward multi-device use. Furthermore, forcing users to use the devices with the best fit for dealing with a simple task forms positive affective appraisals, resulting in a reduction in the detrimental effects of psychological reactance.

The results of this dissertation have several theoretical contributions and provide important guidelines for device manufacturers, such as Apple, Samsung, and Google, and for companies whose employees use multiple devices at work. I hope that this dissertation will inspire future research on this emerging and critical topic.



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