If a person who is eating bread says the Beracha of "Shehakol" or "Borei Minei Mezonoth" or "Borei Peri Ha-adamah", instead of the correct blessing of "Hammosi", he has still fulfilled his obligation.
The complication arises when the person who says the wrong Beracha says it not only for himself, but also on behalf of others who are at the same table. Do they also fulfill their obligation with the blessing he recited instead of "Hammosi"?
The answer depends on how they reacted when he recited the incorrect Beracha. If they accepted it and still had their minds on the blessing he recited, then they fulfilled their obligation. If, on the other hand, when they heard him say the wrong blessing, they stopped paying attention, then they did not fulfill their obligation. The reason being that in order for someone else's blessing to cover another person also, both the one who blesses as well as the one who hears, require the concentration of the heart (Kawwanah).
(See Kaf Hahayim, 167:, Oth 77)
