A specialist in food technology at Massey University in New Zealand in recent times weighed in on this important issue: "Flavor in ice cream is only released when the fat content – which carries the flavor – is warmed in the mouth to at least body temperature," said Kay McMath. "During licking, the tongue is coated with a thin layer of ice-cream which is more rapidly warmed and the flavor is noticed by the large surface area of the taste buds present on the tongue.
In contrast, a spoon provides some insulation to keep the sample colder when the ice cream goes into the mouth. Once inside, the tongue pushes the ice cream to the roof of the mouth to melt before swallowing. This results in a smaller surface area on the tongue involved in warming the ice cream and releasing flavor.
No word yet on how biting into an ice cream cone, our preferred method, affects flavor.