Towards a Neuroscience of Love: Olfaction, Attention and a Model of Neurohypophysial Hormone Action

odor recognition of partners. There was also no similar correlation between their passionate love score and identifi cation of female friends, indicating a sex-specifi c effect. Lundström and Jones-Gotman argue that this specifi c reduction in recognition of opposite-sex friends supports the defl ection theory for the psychological mechanism of romantic love. The defl ection theory proposes that love is accompanied by a decrease in attention toward opposite-sex individuals, in contrast with an alternative idea which postulates intensifi ed attention toward the romantic partner (although, as they acknowledge, these need not be mutually exclusive). Furthermore, they suggest a testable mechanism for this effect through antagonistic effects of the neurohypophysial hormones oxytocin and vasopressin, whereby elevated oxytocin levels, promoted by romantic love and attachment, causes a reduction in levels of bound vasopressin and an associated fall in attention toward individuals of the opposite sex. The race is now on to test this intriguing hypothesis, and to examine whether the effect holds for male responses to female stimuli. Research in this area will also benefi t from using tasks that measure verbalized hedonic perception or subliminal hedonic “decisions” manifested in affective change, in addition to those addressing cognitive processes such as verbal labeling and levels of olfactory recognition. Humans do indeed recognize their own odors, or those of partners, relatives and friends at levels higher than chance (Lenochova and Havlicek, 2008). However, level of performance is signifi cantly lower compared to recognition based on visual appearance or voice: one can imagine how different our world would be if we misidentifi ed our partner as often as one-half to two-thirds of the time (Hold and Schleidt, 1977). Use of hedonic rating scales, measurement of chemosensory event-related potentials (CSERPs) or functional neuroimaging would be illuminating; all these approaches have previously been successfully employed in tests of perception of bodily odors. For example, hedonic ratings (e.g., Roberts et al., 2008; Wedekind et al., 1995) and CSERPs (Krauel et al., 1998; Pause et al., 2006) have been used to explore relationships between genetic dissimilarity in potential mates in perception of axillary odors, while functional imaging has been used to investigate effects of 16androstenes, constituents of axillary odor (e.g., Gulyás et al., 2004). Through the use of such techniques, olfactory processing may hold the key to understanding the neuroscientifi c basis of love.