Just seen this article across various local rag websites, I'm still not quite sure if I understand what they've actually changed though! Surely the barriers indicated a railcard or child ticket in some way previously
www.wakefieldexpress.co.uk

The rail ticket ‘polygraph’: Northern deploys new kit to detect ‘chancers’ using the wrong ticket at station barriers
Automated ticket checks at barriers in Northern-managed stations are about to get smarter thanks to new technology that will alert staff to potential ‘chancers’ using an incorrect ticket.
The rail ticket ‘polygraph’: Northern deploys new kit to detect ‘chancers’ using the wrong ticket at station barriers
Automated ticket checks at barriers in Northern-managed stations are about to get smarter thanks to new technology that will alert staff to potential ‘chancers’ using an incorrect ticket.
The new technology will quickly and accurately check that a ticket is valid, but also alert staff if that validity requires additional checks such as presentation of the appropriate railcard.
Staff will then confirm the ticket is being used correctly, taking the necessary action if it isn’t.
With over 300,000 people using automated barriers across its network every day, checking the credentials of every ticket is a huge task - particularly at the larger stations during rush hour.