you beat me to the question, maninthemiddle.
The WTBTS maintained that heart is not just a pump, it is linked to the brain through nerves and is the actual organ where affections, motivations, desires and emotions are literally formed. (Watchtower3/1/71, p. 133-135)
The Society eventually and quietly abandoned the idea that literal heart is responsible for affections, motivations, desires and emotions. (Watchtower 9/1/84, p. 6).