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Text Advertising Blindness: The New Banner Blindness?

Justin W. Owens, Barbara S. Chaparro, and Evan M. Palmer

Journal of Usability Studies, Volume 6, Issue 3, May 2011, pp. 172 - 197

Article Contents


Analyses

Both performance and eye-tracking metrics were examined. Data from the target‑absent condition were omitted from the analyses.

Task success was dependent on whether the participant clicked on the correct target within the 105 second allotted time limit. If the correct target was selected, then the task was marked as successful. If it was not, then it was marked as a failure.

Task duration was calculated from the onset of the trial to either when the target was clicked, 105 seconds expired, or the participant gave up completing the task and announced that the target could not be located.

Task difficulty was defined by the self-reported difficulty score given after each trial. Trials were scored from 1 to 5 with very easy being rated as 1 and very difficult being rated as 5. Task difficulty was calculated for both search type and target location conditions.

Ad recall was measured from the post-experiment interview. One question asked participants to indicate regions of the website where advertisements were located. A second question asked participants to sketch a prototypical page in the website. If either response indicated advertisements in the top or side advertising areas, it was recorded that the participant recalled ads in that location.

Fixation count was defined as the number of fixations in a particular AOI or on the entire web page. A single fixation was defined by the standard Tobii StudioTM fixation filter, which consists of two or more consecutive sample points that fall within a 35-pixel radius from the averaged sample point location as collected by the Tobii eye-tracker. For a participant located 65 cm from the eye-tracker, the approximate visual angle is 1.66° for the 35-pixel radius fixation. The sample points were defined by binocular location of the point, which was determined by the median location between the left and right eyes of the participant. If only one eye was trackable, then the location of the sample point for that eye was used. If neither eye was available, it was recorded as missing data and was omitted from analysis. Whole page fixation count was defined as the sum of all fixations on a target web page. AOI fixation counts were calculated by summing the number of fixations within an AOI.

Fixation duration was defined as the length of time from the first sample point to when the sample point was located outside of a 35-pixel radius from the averaged location of consecutive sample points. AOI mean fixation durations were calculated by averaging the duration of fixations found within an AOI.

Order of fixations was defined as the rank order the Content AOI, Top Ad AOI, and Side Ad AOI were fixated. The order was determined by calculating the time to first fixation for each AOI and assigning the appropriate rank. In the event the AOI was not fixated, it was omitted from the rankings.

The eye-tracking data were log transformed to correct for leptokurtosis and positive skewness in fixation count and mean fixation duration data. The transformations affected fixation counts and mean fixation duration for whole page and within page AOI analysis. Generally, the log transformations corrected skewness and kurtosis issues with the data.

 

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