Application servers and methods of operating the same are provided for generating a personalized recommendation of items to a first user. An updated rating value N(t) of an initial rating value N(0) is determined for each rated item based on an age of each rating. The updated rating value N(t) is based on a difference between the value of the initial rating N(0) and a neutral rating value R, and on a predetermined half-life of the ratings. The updated rating value N(t) converges towards the neutral rating value R with an increase in the age t for each rating.