I also was just noticing that the OP is talking about a child with processing speed in the 80th percentile or above not a scaled score in the 80s. Although that is considerably lower than scores in the upper 90s on the other indices, it isn't so much lower that I'd be thinking LD. Many of us with kiddos with concerning discrepancies have kids with differences of 50 percentiles or more.
Oh yikes, I read the OP quickly and was thinking "80"s as the actual PSI, not 80th percentile. 80th percentile I most likely wouldn't even blink over - the reason for that amount of dip might be as simple as a 4 year old who's poking along and doesn't understand that they are being timed. Sooo... if that's what happened, I think chances are that you *might* see an increase in processing speed when he's tested when he's older and "gets it" that for that specific set of subtests you need to make your marks quickly and move along. OTOH, I'd beware that there's always a chance with the next round of testing that you'll see another part of the scores actually go down - that's happened with one of my dds (across the board), and for my 2e ds, his PRI vs VIQ scores have been split each time he was tested, but in opposite directions both times. Sooo... just keep in mind, any one test is a snapshot taken on one day - there's always the chance that you don't capture the full picture on any one test.
Best wishes,
polarbear
