Two midfielders will officially join on 1st July, thought to be Kidderminster's Richie Appleby and Cambridge's Ian Ashbee.
Meanwhile two centre backs - both with "good experience in the Scottish Premier League" - will also be joining Jan Molby's ranks. Motherwell's Greg Strong will be one of those, but the identity of the other is unknown. They will become Hull City players on Saturday when their present deals finish.
Pearson said in a statement on the official website: "We are overloaded with centre halves and I know Jan ideally would like to operate with four in the squad and Steve Burton as the developing fifth centre half.
"We have had some interest from other clubs in one or two of our defenders and once we have formally announced our two new arrivals we will work hard to reduce numbers in defensive positions."
Matt Bloomer and Matt Wicks are tipped to go, while Nicky Mohan may have his contract paid off after no interest came in after transfer-listing him. Mike Price, Rob Matthews and Lee Philpott are in similar positions.
Pearson continued: "We want a quality twenty-two man squad all battling for places, not twenty-seven with five or six players who know they are not in the managers plans, potentially affecting squad spirit.
"Jan's team is therefore taking shape but we are still looking for a fourth striker and possibly another left back."
Meanwhile he announced that Gary Barnett has arrived as Jan Molby's assistant manager, and Ed Baroneski has been appointed as fitness coach. The former Leeds United fitness advisor has agreed terms until the end of the season to get the squad in shape and fit for the full season.