7.1.1　Introduction of the experiment equipment and software

The eye-tracking experiments in the book were conducted on a Tobii Eye Tracker（2006 version）with Clear View analysis software in the Eye-tracking Lab in UiL-OTS（Utrecht Institute of Linguistics）at Utrecht University，the Netherlands during June and July，2010.

The Tobii Eye Tracker is an improved version of the traditional PCCR remote eyetracking technology.Its sharpest advantage，compared to other eye-tracking hardware，is that it does not impose any restrictions on the user（such as helmets，head-rests or markers）.This advantage allows a natural user environment and therefore natural user behavior is captured.It also provides good tracking ability，and handles well with people wearing glasses or contact lenses.Since my research purpose requires eye movement data as natural as possible，the advantages of Tobii are important.

In my experiments the Tobii eye tracker monitor is placed in a separate sound-proof booth in the lab，with a keyboard and mouse which allow response tasks and control of pace by the participants.During the recording，the subject sits comfortably in-front of the Tobii at a distance of approximately 60 cm.They were told to try to stay unmoved and that slight movements were allowed and will not disrupt recording.They looked at the stimuli on the monitor and the data of their eye movements are collected by the system automatically.The researcher was at the primary screen outside the booth on which process of the subjects'reading could be seen and monitored.

The software for collecting and analyzing the eye-tracking data in my experiments is Clear View 2.7.1.The Clear View analysis software is designed to provide easy-to-use yet flexible and powerful recording and analysis of eye-tracking data.The ClearView operation window of the Prepare is shown in Figure 7.1.

Once recording is finished，the data collected can be analyzed by the tools available in Clear View.The work-flow of my analysis went through the following steps：

Step 1：Using the different visualization tools（gaze replay，gaze plot and hotspot plot）to get a qualitative view of the data and identify behavior of interest.Gaze replay is a way to dynamically visualize a gaze recording.It replays the gaze path overlaid on top of the stimuli，in this case，each individual page in the slide show.It provides a direct and dynamic view of how the subject looked at the stimuli during the recording process.A gaze plot is a screen shot showing all the fixations a person made on a specific image or webpage.Specifically，graphically fixations are typically represented by dots（larger dots indicate a longer fixation time）and marked with numbers by sequence in the viewing process，whereas saccades are indicated by lines between fixations（see Figure 7.2）.A hot spot or a heat map（see Figure 7.3）uses different colors to show the amount of fixations participants made in certain areas of the image or for how long they fixated within that area.Bright red usually indicates a highest number of fixations or the longest time and green the least，with varying levels in between.

Figure 7.1　The Clear View operation window

Figure 7.2　An example of gaze plot

Figure 7.3　An example of hot spot

Step 2：Defining areas-of-interest（AOIs）to facilitate meaningful data quantification.This is a very useful tool for quantifying eye gaze data on a higher-level analysis.For example，in my experiment a key objective is to compare the eye gaze data in different areas on the advertisement page，such as，the pictorial area and the verbal slogan.So these contents are defined as different AOIs.

Step 3：Making raw text exports or use Direct Excel templates for quantitative analysis and conclusions.Data for text exports include gaze data，eyefiltered data，fixation data，event data，AOI data，AOI list and combined data.The Excel template provided by Clearview is very useful for AOI data analysis.It calculates the descriptive statistics such as mean，min，max of the following measures—fixation count，gaze time，average fixation duration，time to first fixation，and fixation order of each AOI on each page.