The use of eye tracking in conjunction with other biometric devices, provides an objective measure of the performance of packaging. The eye trackers yields a host of metrics that quantify the viewing behaviour of consumers. Other biometric devices supplement this information with metrics pertaining to consumers’ emotions, motivations and level of engagement, as they view the packaging.
The use of these devices is likely to gain momentum as they become more affordable, and as more testing facilities emerge.
Research on shelf impact should be conducted in the store or in a manner where the store shelf is simulated, such as at packaging testing labs. For example, CUshop, at Clemson University’s Sonoco Institute for Packaging Design and Graphics, which uses eye tracking in conjunction with galvanic skin response (GSR), EEG and facial coding.
Shelf impact may also be assessed on virtual shelves populated with digital images of packs. Respondents view these mock-ups on computers coupled with screen-based eye trackers, in a controlled location setting. This approach is more affordable and may be preferable in the early stages of the development process.
If the prime objective is to assess the shelf, respondents are asked to browse the display without prompting for any particular item. On the other hand, to assess findability or the time it takes to find an item, the respondent is prompted to search for the item.
The eye tracker records gaze points, fixations, and the duration and order of fixations. It reveals what the respondent is viewing over the brief time that they browse the shelves. Gaze plots describes the user’s gaze pattern, and heat maps, like the one depicted in Exhibit 24.5, summarize the viewing behaviour of the respondents in terms of “heat intensity”, revealing the red hot spots.
Eye tracking highlights what consumers’ notice, what stands out. However, it does not reveal what consumers perceive or how they feel about the packaging. Do consumers like the packaging? Is it standing out for the right reasons?
Typically, we do not require large samples for eye tracking studies. If the research is qualitative in nature, a sample of 10 to 15 should suffice. For quantitative studies, a sample of 20 to 40 should be adequate.
The size of the sample depends on the variance — we need larger samples if consumers vary greatly on how they look for a product on shelf. This is unlikely to be the case, yet other than prior benchmarks, there is no way to determine the variance prior to the research.
You could however, track variance and aggregated heat maps as you progress, and add more respondents if the variance suggests that you need a larger sample to meet the desired level of significance. Quite often though, you may not find much change in the heat map from a sample of 20 to a sample of 30.
Combining eye tracking with other biometric techniques for measuring consumers’ emotions and motivations, and their level of engagement provides a better-rounded understanding of the impact of packaging on the shelf.
GSR reveals physiological arousal due to excitement, attention or anxiety. EEG detects brain activity revealing respondents’ level of attention and engagement, workload or the extent to which they are mentally stretched, and their motivations in terms of positive-negative feelings and approach-avoidance. Facial coding helps interpret their facial expressions revealing emotions that are outwardly displayed. These techniques are detailed in Chapter Biometrics.