Sony has detailed some of the changes due to be implemented to PlayStation Plus with the arrival of PlayStation 4, telling VideoGamer.com that both auto-updates and the "social features of PS4" will not require a PlayStation Plus subscription to access.

Catch-up TV and online movie services will continue to be free to all PS4 users, although an additional fee may be required to access back-catalogue PS3 titles once the Gaikai streaming service is introduced next year.

A PlayStation Plus account will also be required to access PS4's online multiplayer functionality - something Sony says will allow it to "invest significantly" in PlayStation Network to help lower downtimes and improve its performance.

"It is time to charge, but it is time to charge and still continue to deliver phenomenal value," SCEE UK & Ireland MD Fergal Gara told VideoGamer.com during E3.

"A PlayStation Plus subscriber for PlayStation 4 comes away with a hell of a lot. First of all, the subscription applies across all three platforms [PS4, PS3 & PS Vita], so if you have the three platforms then you have an instant game collection on all three. So that's hugely powerful in its own right. But it is true to say that the online multiplayer element for PS4, you do require the subscription in order to [make use] of that.

"If you choose not to subscribe we are still gating relatively little in many senses, so access to online catch-up TV and online movie services sit outside of the gate, for example. The social features of PS4 and PS4 games sit out of the subscription service... things like auto-updates on PS4 sit outside of PlayStation Plus, so we're trying to be as balanced and as fair as we possibly can. If you choose to pay the subscription, yes, you get one important element of modern-day gameplay, but you also get fantastic value in games, including the PlayStation Plus Edition of DriveClub."

Auto-update functionality had previously only been available to PS Plus subscribers on PS3, and though it isn't yet clear what Gara means by PS4's "social features", it's possible he could be referring to the console's broadcasting and video upload features.

The service seems relatively more open than Microsoft's Xbox LIVE service, too, which blocks users from accessing services like Netflix and 4OD unless they're an Xbox LIVE Gold subscriber.

Whether PlayStation Plus users will be required to pay an additional fee for access to PS3 title streaming through Gaikai, however, is still undecided.

"In short, we haven't decided," said Gara when asked whether the firm plans to introduce additional PlayStation Plus tiers to accommodate backwards-compatibility streaming. "The Gaikai developments are exciting. The Remote Play feature which we're particularly excited about not just benefits PS4 but PS Vita - that uses some Gaikai technology.

"But secondly, the full cloud gaming service comes a bit later - we announced that 2014 will start to see that introduced for PS3 titles in the US, and we'll start to see a gradual increase in consoles, titles, devices and countries involved as we go forward, so there is a plan there to bring the PlayStation experience to more devices out of the cloud using the Gaikai that will broaden over time.

"Will that be part of PlayStation Plus? I genuinely don't know. Will that require some other, different charging mechanism? Perhaps. We just haven't sat down to answer that question yet."

PlayStation 4 launches worldwide this Christmas.