Lövheim classifies emotions according to Silvan Tomkins, and orders the basic emotions in a three-dimensional coordinate system where the level of the monoamine neurotransmitters form orthogonal axes. The model is regarded as a dimensional model of emotion.[4]
The main concepts of the hypothesis are firstly that the monoamine neurotransmitters are orthogonal variables, meaning involving independent pairs of neurotransmitters; and secondly the proposed one-to-one relationship between the monoamine neurotransmitters and emotions.[5]
^Lövheim, Hugo (2012). "A new three-dimensional model for emotions and monoamine neurotransmitters". Medical Hypotheses. 78 (2). Elsevier Ltd: 341–348. doi:10.1016/j.mehy.2011.11.016. PMID22153577.