2 Humans (known as ‘Trackers’) are still used by some retailers to follow customers (discreetly) through stores to see the flow between the various parts of a store, but technology is replacing them. These include video surveillance, thermal sensing, lasers, face recognition and so-called device-based solutions.

Some of these technologies are sophisticated, but still being developed, such as face recognition linked with advanced artificial intelligence (AI) analysis. Others are more common with a proven track record, such as thermal imaging, which detects emissions from moving objects and, because it is not sensitive to light, can work in any space, no matter how well lit. But the technology that has, arguably, the most potential for capturing customer-movement data, is the use of sensors that pick up the unique identifier signals emitted by mobile phones as they automatically seek wi-fi networks that they can join. What do you believe are the advantages and disadvantages of using such technology?