The non-manual markers of predictive/peripheral conditionals are the same of factual, counterfactual, and concessive conditional clauses: raised eyebrows (re), chin down (cd) at the end of the antecedent clause, a signing pause and eye blink between the antecedent and the consequent clause and, optionally, body lean forward (bl-f) over the antecedent clause.
cd
bl-f
re
ix3 3invite1 ix3 angry anymore
‘If I invite him, he’s not angry anymore.’
Since raised eyebrows and chin down also mark polar questions, the lack of a condition linking the antecedent to the consequent clause, as well as the lack of manual conditional markers, might induce ambiguity in its interpretation between a non-predictive conditional clause and a polar interrogative (SYNTAX 1.2.1) followed by a declarative clause (SYNTAX 1.1), as in the following example.
cd
re
hunger ix2 eat palm_up be_able palm_up
‘If you are hungry, you can eat.’
‘Are you hungry? You can eat.’