I would say no, fright is something instinctive; a shying away from fire, elephants or camels if you are a horse. And from berserkers if you are a human, the anormal and dangerous, by sheer instingt like you shy away from a snake or tarantula or get goosebumps or whatever, something that can only be overcome by bravery or training.
Spears deterring cavalry is not from fright- they are no more frightening than any other wall of men to a horse. It is the rider thinking "Hmmm... if I charge unto long and pointy things we will die, I better circle round them or charge somewhere else", it is not from fright, just sheer tactical sense.
Let us not mix the two. Phalanxes are over-effective already, no need to add something instinctive that is no worse than any other massive and tight formation of infantry.
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