On clinical examination 42 per cent of the mothers of 32 children with L.O.P. were regarded as introverted, but only 13 per cent of the mothers of 46 children with I.P.
Twenty L.O.P. mothers and 26 I.P. mothers were tested with the M.P.I. which confirmed the introversion of mothers of the L.O.P. group. There was a higher percentage of sensitive, suspicious parents in this group. More parents of I.P. children were over-protective.
These findings are believed to support the differentiation of childhood psychotics into distinct diagnostic categories.