by John BIERS Agence France-Presse NEW YORK, United States (AFP) — Why did you splurge on that new pair of shoes? Or that pricey smartphone? More and more advertisers are trying to tap into the unconscious to divine the invisible forces that drive those spending decisions. Using gadgets to track eye movements, computer maps of faces to capture a momentary grin (approval) or squinting (anger), and sensors to measure perspiration or monitor brain activity, companies […]