Liam Jones

In order to judge how behavior caused by the positivity effect should be considered, comparisons were made between the positivity effect and two mental disorders. These disorders, Tourette’s syndrome and psychopathy, were selected due to their extreme differences in what Strawsonian attitudes they inspire and how they are perceived relative to disordered patients’ will. Disorder-affected behavior of Tourette’s patients inspires the objective attitude and is seen as a condition affecting an individual’s will, while disorder-affected behavior of psychopaths inspires the interpersonal attitude and is seen as a character trait. Relevant distinctions between psychopathy and Tourette’s syndrome were found to include their neurological causes, the obviousness of the suffering they caused, and how easily their disorder-affected behavior could be mapped onto goal-seeking behavior. These considerations suggest the positivity effect should be viewed similarly to psychopathy in terms of responsibility, although this is complicated by its time of development and other factors.

Metabolic pathways underlying brain function remain largely unexplored during neurodevelopment, predominantly due to the lack of feasible techniques for use with awake infants. Broadband near-infrared spectroscopy provides the opportunity to explore the relationship between cerebral energy metabolism and blood oxygenation/haemodynamics through the measurement of changes in the oxidation state of mitochondrial respiratory chain enzyme cytochrome-c-oxidase alongside haemodynamic changes. We used a bNIRS system to measure ΔoxCCO and haemodynamics during functional activation in a group of 42 typically developing infants aged between 4 and 7 months. bNIRS measurements were made over the right hemisphere over temporal, parietal and central cortical regions, in response to social and non-social visual and auditory stimuli. Both ΔoxCCO and Δ[HbO2] displayed larger activation for the social condition in comparison to the non-social condition. Integration of haemodynamic and metabolic signals revealed networks of stimulus-selective cortical regions that were not apparent from analysis of the individual bNIRS signals. These results provide the first spatially resolved measures of cerebral metabolic activity alongside haemodynamics during functional activation in infants. Measuring synchronised changes in metabolism and haemodynamics have the potential for uncovering the development of cortical specialisation in early infancy.