Zwitserlood, P. | bioRxiv Science

bioRxiv2020

Women show enhanced attractiveness ratings and neural processing of male faces associated with male chemosensory signals

There is growing evidence that humans use olfactory chemosensory signals for social communication, but their role in affective associative learning is largely unknown. To examine this, women implicitly learned face-odor associations by pairing different neutral male faces with either a male chemosignal presumably involved in human mating behavior (dissolved {Delta}4,16-androstadien-3-one, "AND"), a pleasant smell (dissolved vanillin) or the neutral solvent alone. After learning, women rated faces previously paired with AND or vanillin as more attractive than faces paired with solvent, even though they were unable to identify the contingency of face-odor pairings above chance level. On a neurophysiological level, both AND- and vanillin-associated faces evoked stronger magnetoencephalographic correlates of enhanced emotional attention than solvent-associated faces at early (<120 ms) and mid-latency (140-270 ms) processing stages. This study stresses the role of AND as a human chemosignal in implicit social communication and demonstrates its effectiveness in modulating emotional learning.

neuroscience↗

bioRxiv2019

Disentangling semantic and response learning effects in color-word contingency learning

It is easier to indicate the ink color of a color-neutral noun when it is presented in the color in which it had been shown frequently before, relative to print colors in which it had been shown less often. This phenomenon is known as color-word-contingency learning. It remains unclear whether participants actually learn semantic (word-color) associations or/and response (word-button) associations. We here present a novel variant of the paradigm that can disentangle semantic and response learning, because word-color and word-button associations are manipulated independently. In four experiments, each involving four daily sessions, novel words (pseudowords such as enas, fatu or imot) were probabilistically associated either with a particular color, a particular response-button position, or with both. Neutral trials were also included, and participants awareness of the contingencies was manipulated. The data showed no impact of explicit contingency awareness, but clear evidence both for response learning and for semantic learning, with effects emerging swiftly. Deeper processing of color information, with color words presented in black instead of color patches to indicate response-button positions, resulted in stronger effects, both for semantic and response learning. Our data add a crucial piece of evidence lacking so far in color-word contingency learning studies: Semantic learning effectively takes place even when associations are learned in an incidental way.

neuroscience↗