These factors can be something about the person or something about the situation, which can combine [to determine] the consumer's motivation [to process] product-related information at a given point in time.
I think the first infinitive clause to determine the consumer's motivation serves as a purpose adjunct.
But I am not sure about the second infinitive clause,
to process product-related information at a given point in time.
Does it also serve as a purpose adjunct ?
Or is it adjectival and add information to the consumer's motivation, telling which kind of motivation.