Measurement practices in hallucinations research

Introduction: In several sub-fields of psychology, there has been a renewed focus on measurement practices. As far as we are aware, this has been absent in hallucinations research. Thus, we investigated (a) cross-study variation in how hallucinatory experiences are measured and (b) the reliability of measurements obtained using two tasks that are widely employed in hallucinations research.Method: In Study 1, we investigated to what extent there was variation in how the Launay-Slade Hallucination Scale (LSHS) has been used across 100 studies. In Study 2, we investigated the reliability of the measurements obtained through source monitoring and signal detection tasks, using data from four recent publications. Materials are available at doi: 10.17605/osf.io/d3gnk/.Results: In Study 1, we found substantial variation in how hallucinatory experiences were assessed using the LSHS and that descriptions of the LSHS were often incomplete in important ways. In Study 2, we reported a range of reliability estimates for the measurements obtained using source monitoring and signal discrimination tasks. Some measurements obtained using source monitoring tasks had unacceptably low levels of reliability. Conclusions: Our findings suggest that suboptimal measurement practices are common in hallucinations research and we suggest steps researchers could take to improve measurement practices.

Сognitive Style Differences in Detection and Discrimination of Sensory Signals

The purpose of the study was to test individual differences in sensory sensitivity while performing signal detection and signal discrimination tasks. A total of 98 subjects performed two cognitive style tests on flexibility and rigidity of cognitive control, and focusing and scanning control, as well as two psychophysical tasks on visual signal detection (“yes/no” method) and loudness discrimination (“same/different”), each including two difficulty levels. Task type and difficulty level were considered as stimulation factors, and cognitive styles were considered as individual differences factors. The effects of both cognitive styles along with the effect of their interaction were revealed. ‘Flexible’ subjects and ‘scanners’ showed higher sensitivity in signal detection compared to ‘rigid’ subjects and ‘focusers’, respectively. Whereas no between-group differences were found in the accuracy of signal discrimination. Thus, we revealed individual differences in sensitivity, driven by cognitive style characteristics on the one hand, and task type on the other.

Antinociceptive modulation by the adhesion GPCR CIRL promotes mechanosensory signal discrimination

Adhesion-type GPCRs (aGPCRs) participate in a vast range of physiological processes. Their frequent association with mechanosensitive functions suggests that processing of mechanical stimuli may be a common feature of this receptor family. Previously, we reported that the Drosophila aGPCR CIRL sensitizes sensory responses to gentle touch and sound by amplifying signal transduction in low-threshold mechanoreceptors (Scholz et al., 2017). Here, we show that Cirl is also expressed in high-threshold mechanical nociceptors where it adjusts nocifensive behaviour under physiological and pathological conditions. Optogenetic in vivo experiments indicate that CIRL lowers cAMP levels in both mechanosensory submodalities. However, contrasting its role in touch-sensitive neurons, CIRL dampens the response of nociceptors to mechanical stimulation. Consistent with this finding, rat nociceptors display decreased Cirl1 expression during allodynia. Thus, cAMP-downregulation by CIRL exerts opposing effects on low-threshold mechanosensors and high-threshold nociceptors. This intriguing bipolar action facilitates the separation of mechanosensory signals carrying different physiological information.