Dear Suan,

Thank you for the quotations.

I agree that such 'mental associates' of citta as phasso, vedanaa,
saññaa and cetanaa arise at the same time. This is determined by the
type of cause-and-effect links between phasso and three other
citta-sa"nkhaaraa. Since phasso is necessary and sufficient condition
for these three, they necessarily arise together.

Vitakka may arise or not. It depends.

In the previous message I wrote that the input signals are
simultaneously processed by vedanaa, saññaa and cetanaa.
As it said by Buddha: "phu.t.tho, bhikkhave, vedeti, phu.t.tho ceteti, phu.t.tho
sañjaanaati" (SN 4.68).

On the chart http://dhamma.ru/lib/paticca.pdf you see conditional
relations between citta-san"khaara's.

Those relations are clearly stated in the suttas to be temporal, as in:
"Phassasamudayaa vedanaasamudayo, phassanirodhaa vedanaanirodho".

The fact that contact (phasso) arises a little before other
citta-sa"nkhaara's is also confirmed by my personal experience, and
some knowledge of neurophysiology.

Best regards,
Dimitry