Yang started in Celtic’s 3-1 win over St. Johnstone over the weekend but faced the wrath of Brendan Rodgers at the break and was taken off at half-time.
He has started seven league games since joining Celtic in the summer and has scored just once in the Scottish Premiership so far this season.
Hartson stressed the importance of the attacker reacting to the adversity in a better way as he is insistent that there is talent in the player, which has only been seen in glimpses.
The former Celtic star conceded that if Yang does not show more consistency going forward the opportunities will eventually dry up at Parkhead for him.
Hartson said on the Go Radio Football Show: “Yang needs to react in the right way if he is getting opportunities.
“We have seen glimpses of him, taking players on, getting crosses in, cut inside – he is a player with a little bit of talent.
“But he needs to do it more often or otherwise he will find himself out of the team.”
Yang has featured 18 times for Celtic this season but is yet to make a defining impact on the team.