Frequently Asked Questions (FAQs) on Eye-Tracking
What are the key differences among eye-tracking technologies for central location studies?
From a technology/equipment standpoint, a major difference and issue to consider is the size at which stimuli is shown. With some “stationary” eye-tracking units, consumers view images shown on computer monitors (typically ranging from 20 to 30 inches wide). While this approach may be appropriate for web usability testing, PRS has found that nearly life-size scenes (at least 80% of actual size) are needed to gather accurate measures of in-store or shelf visibility. Therefore, PRS shows images at 6-feet/2 meters wide (via high-resolution and high-definition LCD projection) for eye-tracking in packaging and shopper research studies.
What eye-tracking equipment does PRS use? Why?
PRS uses a proprietary eye-tracking system, which we developed/pioneered and have continually enhanced over 30+ years. Today, PRS has over 80 stationary eye-tracking units globally with identical technology, all of which are operated by trained personnel supported by PRS’ internal eye-tracking support team. This team regularly compares PRS Eye-Tracking technology to other units in market – and we’ve consistently found the PRS units to be superior in accuracy. The primary difference is the calibration process: Unlike other systems, the PRS Eye-Tracking system mandates that calibration is validated (to within 14-20 pixels of target area) before each respondent proceeds. Thus, the PRS system isn’t dependent upon the operator’s skill or judgment - and doesn’t allow for gathering inaccurate readings.
More technical specifications follow:
PRS Binocular-Free Head Eye Tracking System – Technical Specifications
|
Accuracy |
0.5 degrees |
|
Drift |
<0.1 degrees |
|
Data Rate |
60 Hz |
|
Freedom of head movement |
1 cubic ft |
|
Binocular tracking |
Yes |
|
Dark Pupil Tracking |
Yes |
|
Panasonic PT-AE4000U Display Size |
72”x39” |
|
Projection Resolution |
1920x1080 |
What are recommended sample sizes for eye-tracking? Can eye-tracking be used qualitatively?
When eye-tracking is used as part of quantitative validation studies (for new packaging, shelving or merchandising systems), PRS strongly recommends conducting multi-cell monadic studies, with minimum samples of 100 shoppers per option. Quantitative samples are needed to accurately gauge shelf visibility – and these measures must be gathered on a monadic basis: If shoppers see the same category twice, they will often look to see what has changed, thus leading to artificial viewing patterns and biased/ inaccurate results.
PRS does utilize eye-tracking as a complement to qualitative screening studies, to gauge primary viewing patterns (i.e. starting points, dominant paths, messages/elements frequently missed, etc.) and to provide input for design optimization. In addition, PRS Mobile Eye-Tracking (see below) is often applied on a qualitative basis, to uncover insights regarding in-store shopping behavior.
What is mobile eye-tracking? How does it differ from eye-tracking in central locations?
Mobile eye-tracking utilizes a different technology than “traditional” eye-tracking and generates different outputs. A pair of light-weight glasses is used to create a video-tape of each shopper’s in-store experience (including his/her focal points and viewing patterns) – and these tapes are then analyzed to generate findings. PRS Mobile Eye-Tracking is unique in having solved the parallax issue, as it provides accurate readings when shoppers shift from looking down an aisle to viewing individual packages/products in hand.
The primary benefit of mobile eye-tracking is that it can be used in actual store environments, to uncover shopping patterns and/or engagement with POS materials. Therefore, it is a complement to central location eye-tracking, which is typically used to “pre-test” new options prior to their introduction.
What is Web eye-tracking? Can eye-tracking be done via the Internet?
Several companies are now exploring the viability of conducting eye-tracking studies via the Internet, using webcams. To date, these technologies are in their infancy and accuracy has not reached acceptable levels. However, PRS will continue monitoring developments, in order to gauge viability and recommended applications.
Other companies are using the term “Web eye-tracking” in a misleading way, as their technology does not involve tracking actual eye movement. Instead, it refers to a very different process, in which respondents are asked to click on parts/ sections of a pack (or ad), in the order in which they believe to have viewed it. This process does not accurately reflect viewing patterns, as it relies on self-reported behavior (rather than actual documentation) - and on mouse clicks/movement (which can not nearly match the speed/scope of human vision and cognition).
Today, When PRS implements web-based packaging studies, PRS Eye-Tracking of pack viewing patterns is often run in parallel, as an added-value component. However, eye-tracking data itself is gathered via in-person interviews, not via Web.
If you have any questions about eye-tracking, please contact Jonathan Asher (jasher@prsresearch.com) at 201-720-2724. You can also visit www.prsresearch.com to find information and articles sharing insights from PRS Eye-Tracking and PRS Mobile Eye-Tracking studies.