The newest issue of the Am J of Clinical Nutrition had an article entitled,
"Feeding formula without arachidonic acid and docosahexaenoic acid
has no effect on preferential looking acuity or recognition memory in
healthy full-term infants at 9 mo of age.  Haven't read the entire article
yet, but thought you'd like to read what's in the abstract.

The abstract:"Preferential looking acuity and novelty preference were
determined by using Teller Acuity Cards and the Fagan Test of Infant
Intelligence respectively, for 399-433 healthy full-term infant at 39 plus or
minus 1 wk. of age.  Duration of BFing and age of infant at introduction
and amount and type of formula were determined by questionnaire.  74
(17%) never BF; another 92 (21%) were still receiving breastmilk as the
milk source at 39 wks of age.  There were no differences in visual acuity
or novelty preference among the infant when they were stratified by
incidence or duration of bfing..."(The formula used did not contain
docosahexaenoic or arachidonic acid.) "The studies indicate that
formulas containing adequate linoleic and linolenic acids, w/o arachidonic
or DHA, impose no measurable deficits in performance in these visual
and cognitive developmental tests at 9 mo of age in healthy full-term
infants.  "

Innis SM, et al:Feeding formula without arachidonic acid and
docosahexaenoic acid has no effect on preferential looking acuity or
recognition memory in healthy full-term infants at 9 mo of age. Am J Clin
Nutr 64:40-6, 1996.