Psychological Line is an indicator developed by Ken Muranaka

The indicator’svalues may range from 0 to 100. It is a simple indicator which shows the numberof increasing/decreasing prices over a specified period; thereby is a means for deter-mining the overbought/oversold price level.
The standard calculation of theindicator is as follows:

PSL = n / 12 * 100

where n is the number of days that the price is closed higher than the previous period.

n and the number of comparison days (i.e. 12) in the above calculation are subject to change.

https://www.questia.com/magazine/1G1-63024940/opinion-oscillator