The Contribution of Thumbnail Image, Mouse-over Text and Spatial Location Memory to Web Page Retrieval in 3D
A recent study in 2001 conducted by Microsoft Research explored the contribution of thumbnail images on information retrieval of previously stored web pages using various visual cues.
The study involved nine subjects, all of whom participated in a previous study. The subjects were asked to retrieve among the 100 web pages stored in the first session. 50 pages were selected randomly from PC Magazine’s list of top web sites and fifty pages selected randomly from the Yahoo! database. In order to qualify for participation in the initial study, all users had to successfully answer a series of screening questions pertaining to web browser and Internet knowledge. Subject ages ranged from 18 through 50 years old, and all had normal or corrected-to-normal vision. There were 5 females in the return sample.
During the test session, participants were shown one of four different retrieval cues and asked to find the related page. The four retrieval cueing conditions were: the title of the page, a one or two sentence summary of the page’s content, a thumbnail image of the page, and all three cues simultaneously. Participants saw 25 trials of each cueing condition, for a total of 100 retrievals.
The web pages to be stored and the subsequent retrieval cues were presented in a random order for each participant. If a participant could not find the target page within two minutes, a "time-out" was enacted and the participant was instructed proceed to the next retrieval task. Users were not explicitly discouraged from producing incorrect retrievals. This version of the study was run in blocks of 10 trials, with the display alternating between having a thumbnails "on" and a thumbnails "off".
Four main dependent variables were used in this study: (1) web page retrieval time; (2) the number of incorrect pages selected prior to finding the correct page; (3) the number of trials for which the participant failed to retrieve the correct page within the two minute deadline; and (4) the participants’ subjective ratings of the software.
The findings suggest a significant improvement in retrieval time with the inclusion of thumbnail images. Subjects were able to locate the designated web page faster and easier in almost every attempt.
"We examined the contribution of the thumbnail image to the speed and success of finding the target web page [...] We observed an initial significant slowdown in retrieval times when the thumbnail images were not available for inspection. It is clear that the significant drop in performance was due to the thumbnail cueing condition only."
"[...] removing the thumbnail images led to significantly longer reaction times. A significant effect of retrieval cue type was evident, and a significant interaction between visibility of the thumbnail and retrieval cue type was found. [...] In other words, thumbnail images were more important for speedy retrieval."
Incorrect Retrievals & Failed Attempts
The number of failed attempts doubled when the subjects were asked to re-locate the web pages without the thumbnails but relying only on title and summary. The study shows that thumbnails significantly improve the accuracy of information retrieval.
"In addition, looking only at the results of the second visit, with repeated measures showed that removing thumbnail images led to significantly more failed retrievals."
After retrieving all 100 web pages, subjects were asked to fill out a subjective questionnaire in each session. A rank of 1 meant that a feature was considered the best for retrieval, 4 was the worst ranking.
"On average, subjects ranked the thumbnail images as the most helpful, followed closely by the mouse-over text and the spatial location of the web page."
"Taking the pictorial thumbnail images away initially led to a significant drop in subjects’ ability to find the pages. When the thumbnail images were turned off, performance was disrupted. This is quite interesting, given that subjects often chose the thumbnail image as their preferred cue."
The study suggests new and more effective methods for information retrieval complementing the traditional title and summary layout. Thumbshots clearly help improve information retrieval and user satisfaction.