Former Newcastle assistant Pearson sent his team out with an attacking 4-3-3 formation, but it was not enough as they were run ragged by a solid Plymouth Argyle side.
The stunned Saints fans booed their team off at the break and even booed them when they came back onto the pitch for the second half and it is hard to see where the next point is coming for them.
Ironically enough, Southampton started the game brighter and went close through defender Andrew Davies and England Under-21 international midfielder Andrew Surman, who hit a magnificent 35-yard shot just wide of the right-hand post.
All their good work went to pieces however in two minutes.
Surman inexplicably lost the ball in the centre of the park and Plymouth captain Lilian Nalis fed Peter Halmosi, who finished sweetly from ten yards in the 31st minute.
Within two minutes, Plymouth doubled their lead as sorry Southampton once again hit the self-destruct button.
Midfielder Jim Paterson hit a speculative 25-yard shot that Kelvin Davis thought would be blocked by his defence, but was horrified to see the ball go past him and into the back of the net.
This was the cue for hundreds of disgruntled Southampton supporters to stream out of the ground with barely a third of the game gone.
Pearson changed formation at half-time and went back to a more conventional 4-4-2 with Adam Hammill replacing the ineffectual Bradley Wright-Phillips.
But the move had little effect as Plymouth still looked the more likely team to score.
Southampton hit back late in the game and defender Wayne Thomas blazed his side's best chance over the bar from six yards in the 60th minute.
The miss summed up Southampton's night and they must arrest this slide down the table or they will be playing League One football next season.