Participants: One hundred and one undergraduates from James Cook University Singapore (JCUS) were recruited for the purposes of this study. PRS data from two participants (1.98%) were removed due to errors in task completion or missing data. Accordingly, RT data of these 2 participants, along with other repeated trials in the RT data were also removed (7.62%). The final sample consisted of 99 participants (60.60% females, 39.40% males). Their ages ranged from 17 to 34 years (M = 22.48, SD = 2.64). Participants were mostly recruited through convenience sampling via the JCUS Research Recruitment Board and the SONA research management system (SONA, 2018) while the remaining participants were recruited through snowball sampling. Eligible students were allocated credit points for their participation in the study while the remaining participants received no incentive or reward.

Design: This study employed a 3 x 2 within-subjects experimental design with environment type (built, natural or mixed) and mystery (high or low) as the independent variables (IVs). The dependent variable (DV) was attention restoration, which was operationalized in three different ways: (1) perceived attention restoration measured by participants’ scores on the PRS; (2) mean accuracy of participants’ scores on the DSST measured by number of correct responses identified; and (3) mean speed of responses on the DSST. The study was designed to examine the effects of environment type and mystery on attention restoration in cognitively fatigued individuals. Cognitive fatigue was generated through performance of the DSST. The different types of environments were operationalised as such: (1) Built environments are human-made surroundings such as those with architectural features ranging from buildings and roads to parks; (2) natural environments are landscapes usually untouched or conserved by mankind, usually characterised by an abundance of plants and other elements of natural ecosystems; and (3) mixed environments are a 50/50 combination of built and natural elements [67]. Images should be at least 75% natural or built to be classified as natural or built environments respectively.
Mystery refers to settings that easily capture an individual’s attention, providing the prospect to acquire additional information and enhance one’s sense of involvement. High mystery settings usually contain partially concealed views, enticing a person to go further [3]. Examples include a bend in the trail, meandering streams or winding city streets or staircases.

Procedure: This study was approved by JCU Human Research Ethics Committee (Approval Number H7286). This study was conducted in one of the testing rooms within the cognitive psychology research lab at JCUS. There were ten cubicles in the room. Each participant was provided with a desktop computer, a table and chair at each cubicle such that there were no noise interference or other distractions. First, participants were directed to the computer screen on Qualtrics [68] where the information sheet detailing the nature of the experiment was presented. They were given time to read and clarify doubts before providing informed consent by clicking onto the ‘agree’ button, thereby proceeding with the experiment. Participants were then directed to complete demographic information such as their age and gender. Following this, they were directed to an alternative webpage to complete the first DSST on Inquisit, to help familiarise themselves with the task and to initiate cognitive fatigue. Prior to each DSST task, participants were instructed to enter their eight-digit student identification number followed by a dash and the image number (e.g. 123XXXXX-image number for JCU participants; 00000001-image number for external undergraduates) to link performance on the DSST to the environmental image stimuli provided on Qualtrics. Since there was no image prior to the first task, participants were instructed to enter their student identification number followed by the number zero (e.g. 123XXXXX-0 or 00000001-0). Participants were seated approximately 60cm from the computer screen, where they were instructed to pay attention to the key provided at the top of the screen and to proceed with the practice trial followed by the first experimental trial. After completion of the first DSST (fatiguing task), participants were redirected to Qualtrics where the first image stimulus was shown on the screen. Images were randomized so that each participant viewed them in a different order. Each image was shown for 10 seconds before it disappeared. This duration of exposure to the stimulus was deemed sufficient as there was a significant relationship found between scene and recognition performance scores at 10 second durations [52]. Following the stimulus exposure, participants were redirected to Inquisit to complete the DSST following the first image. As such, the DSST performed a dual function as pre-exposure cognitive fatigue task and as a post-exposure measure of cognitive restoration. After completion of the DSST measuring cognitive restoration, participants were directed back to Qualtrics to complete the PRS as a measure of perceived restoration. A smaller version of the image was provided at the top of the screen to prompt their memory and to ensure responses referred to the correct image. This sequence was followed for each of the 18 images. On completion of these tasks, participants were debriefed, thanked for their participation and dismissed.

Software/equipment used to create/collect the data: Qualtrics Inquisit version 4

Software/equipment used to manipulate/analyse the data: SPSS version 23