Positive emotions have different impacts on mood and sympathetic changes in crying from negative emotions

Non-invasive assessment of positive affective state using infra-red thermography in rats

With recent increased focus on positive welfare in animal welfare science, there is demand for objective positive welfare indicators. It is unclear whether changes in body surface temperature can be used to non-invasively identify and quantify positive states in mammals. We recorded continuous measurements of tail surface temperature using infra-red thermography (IRT) and concurrent behavioural observations in male and female Wistar rats (Rattus norvegicus). If tail surface temperature can differentiate between positive and negative experiences, we expect a qualitatively different response compared to negative experiences. Three groups of rats were presented with increasing magnitudes of food rewards (neutral/none, one and three rewards). The rats were placed in an arena to which they were habituated and filmed for 30 s before and 30 min after exposure to different rewards. Tail temperature initially decreased from the pre-reward baseline and subsequently returned towards baseline temperature. The overall pattern of the change was the same as for rats subjected to negative stimuli in previous studies. Nevertheless, dynamic changes in tail temperature, specifically the rate of recovery and the behavioural response (exploration), differed between neutral and rewarded rats but failed to distinguish reward magnitude. Sex differences were found in both thermal and behavioural responses, unrelated to reward magnitudes. Female rats exhibited a greater initial response with a slower recovery than male rats, emphasising the value of using of both sexes in animal welfare research. This study improves our understanding of the effects of positive emotions induced by food reward on peripheral body temperature and behaviour.

Tears of Joy as an Emotional Expression of the Meaning of Life

This article describes a research project in which a qualitative research was carried out consisting of 24 semi-structured interviews and a subsequent data analysis using the MAXQDA software in order to investigate a particular dimorphic emotional expression: tears of joy (TOJ). The working hypothesis is that TOJ are not only an atypical expression due to a "super joy," or that they are only an attempt by the organism to self-regulate the excess of joyful emotion through the expression of the opposite emotion (sadness), but that it is an emotional experience in its own right-not entirely overlapping with joy-with a specific adaptive function. Through the interviews, conducted in a cross-cultural context (mainly in India and Japan), we explored the following possibility: what if the adaptive function of crying for joy were to signal, to those experiencing it, the meaning of their life; the most important direction given to their existence? The material collected provided positive support for this interpretation.