Vita's 512MB of RAM enables it to run programs in the background while gamers are playing games, Sony has said.
One of those programs is cross-game voice chat via Vita's Party system.
"Part of the reason [for including 512MB of RAM] is more RAM means easier development for game developers," Sony president of Worldwide Studios Shu Yoshida told Eurogamer at Gamescom.
"But as important as that is to allow the PS Vita always to do more while the game is running in the background, or when you switch between the game and other applications or system software functionalities.
"So the reason why we were able to include something like Party, which enables cross-game voice chat, is because we designed Vita so it always has enough resources to handle something like that behind the game while it's running."
At Gamescom Sony revealed the final specifications of Vita, set for launch in Europe in early 2012.
The confirmation of 512MB of RAM ended months of speculation about the power of the machine, speculation sparked by a comment by a developer that appeared to back up murmurings that Sony had halved the amount of memory in Vita.
The RAM reduction rumour began in May when a French source said Sony had lowered the base Wi-Fi Vita model's RAM from 512MB to 256MB to lower the cost of the unit to compete with Nintendo's 3DS.
But according to Yoshida, Sony never even considered cutting the amount of memory powering the portable.
"It has been very funny," he said. "There were some rumours for the last few months. Some developer mentioned the RAM was halved. We never announced the amount of RAM, and we never changed it.
"We've been making games, right, and we've been showing the games, like Uncharted, since January. If RAM gets cut in the middle of development, there's no way we can complete the games. So I was like, what's going on?
"I got lots of Tweets saying, Sony made a huge mistake by reducing the amount of RAM. We never talked about the amount of RAM and we never cut it.
"So going into Gamescom we agreed there was no reason we should hide it, so we just added it to the specifications. We always had 512MB of main RAM and 128MB of V-RAM. Actually when you add them together, PS Vita has more RAM than PS3 [the PS3 has 256MB of XDR DRAM main memory and 256MB of GDDR3 video memory]."
The speculation around Vita's RAM caused some concern over the power of the final version of the machine. Yoshida moved to reassure gamers about this.
"So far we've been getting very positive reactions from our developer and publisher partners," he said. "We could put even more power into the portable, but there has to be a balance made between the size of the unit, the weight and the amount of time you can play. We think we've hit the right balance in terms of creating a great experience on the PS Vita.
"The PS3 provides a full HD experience. The resolution on the PS Vita screen is much lower. Even though it's four times the resolution of PSP, compared to the console, the amount of data you have to push is much smaller. So that works to the advantage of the PS Vita."