The 35-year-old midfielder accepted that he and his team-mates were outplayed and outmanoeuvred when the Spanish side took the first leg 2-0 in San Sebastian a week ago.
But with a 20,000 crowd believing that great escapes are possible, Robson called upon his callow colleagues to overcome any dread that might be creeping into their pre-match thoughts as they prepare to face a team which came seventh in the Primera Division last season.
He recalled his Champions League debut with Celtic in February 2008 - only his second appearance for the team following his high-profile transfer from Dundee United - when he thrived in the Parkhead atmosphere, with Barcelona providing the opposition.
His looping header from Aiden McGeady's assist sailed over Victor Valdes to put Celtic ahead, although they eventually lost 3-2.
Lionel Messi, Celtic fans will remember, scored two goals either side of a Thierry Henry strike that night.
"It was a real baptism of fire," Robson said. "It was all new to me but as the game wore on I felt more comfortable with it and the rest of the boys said the same.
"Once you get through that you learn from the experience and I know we have learned from last week.
"We know what to expect now. We watched a lot of videos of Real Sociedad, but a lot of those matches were pre-season games and you could see how they lifted the tempo when it was for real.
"The manager had warned us, but this is a learning curve and it will help us for this game.
"The lads are all positive. We feel if we could get an early goal it could spook them."
Robson had not, however, entered the realms of fantasy and reminded himself not only how good Sociedad were seven days ago, but of the gulf between football in Scotland and Spain.
"They are up there with any team I have played," he added. "They have just sold a player [Antoine Griezmann, to Atletico Madrid] for £24m and although the rest might not be household names they are top-quality players.
"They beat Barcelona last season and played in the Champions League, so we need to be realistic about the task in front of us.
"But that doesn't detract from the fact if we go about our business we can win the game."
Derek McInnes, the Aberdeen manager, did not demur from that rallying call of sorts and pointed to the importance of the first goal - which could either reignite or douse this tie depending, of course, which side scores it.
"We have got to try and impose ourselves on the game," McInnes said. "We are well aware Real Sociedad are in pole position.
"They don't need to do anything different whereas we do, and we need to try and force the issue.
"But we will try and be measured, and it is important we are brave without being reckless, get the balance right.
"We need to utilise the crowd, play a lot more of the game in their half and try and ask questions of them.
"The first goal is key. If we get it, then it is game on and it might just plant a seed of doubt into one or two of them.
"If they were to get it then the job becomes extremely difficult."
The trick for McInnes tonight will be to find the middle ground between caution and bravado in Aberdeen's efforts to effect a rescue.
"It is not all about blood and thunder and going gung ho," he said, "but there is a need to be brave.
"We have to get on the ball, we have to help one another in possession of the ball, ask more questions of them defensively and make sure they don't enjoy it.
"I think if they come here and start to enjoy the game then good players will be allowed to be good players.
"We have to get after them and make things more uncomfortable for them than it was in San Sebastian."