The decision on how much consumers should pay to upgrade their PS3 games to PS4 versions will be made by publishers, according to Sony.
The platform holder announced an upgrade offer during its Gamescom press conference earlier this week, when it said PS4 versions of participating titles will be offered to consumers at significant discounts if they already own a PS3 copy.
In an interview with Digital Spy, Sony UK managing director Fergal Gara explained that Sony would not be setting an upgrade price, and that the decision to implement one would rest entirely with the publisher.
"The publisher gets to define that, actually," Gara said. "What will happen is, the PS4 digital file will be made available on the PlayStation Store (as it would be anyway) at launch, and the PS3 discs will be sold through retail.
"What the consumer can then do, for a premium to be defined by the publisher, is access the PS4 digital game and then, provided they still have the PS3 disc, they will be able to play the PS4 version when they decide to buy the next gen.
"Time window and price window has yet to be defined. Time window is probably more business policy for PlayStation, perhaps, but the premium will be defined by the publisher."