Dwell time is the in-store equivalent of time on page. For each trip and each zone it is the difference between the moment the shopper entered and the moment they left, so it can be reported for a department, a category or a single bay. It is not the same as visit duration, which covers the whole trip from the entrance to the checkout.
Shoppermotion measures it from anonymous trolley and basket positions: tags on the shopping tools are located by ceiling antennas with sub-metre accuracy, and every trip records when it entered and left each zone. Reports show the median and the distribution rather than the average, because a few very long visits easily distort averages. The dwell time article in the Help Center explains the definition in detail.
Dwell time is a proxy for attention, but it should never be read alone. A category where dwell grows while conversion falls is often suffering from choice overload or missing references, and a drop after a relayout may mean the category is easier to shop or that it lost interest. That is why it sits next to the conversion funnel and engagement, and why it should only be compared between zones of similar size and segmented by shopping mission.
In one example on our blog, 49.83% of visitors passed by the Fruit and Vegetable section, with an average dwell time of 1 min 45 s (read the analysis). In the main aisle study, dwell time and predominant flow direction were the key variables used to evaluate category performance and the placement of displays.