In second order conditioning next to a CS1 + US also a CS2 + CS1 association is learned so that also CS2 will cause a CR. Is the order in which the stimuli associations are learned (CS1 + US and CS2 + CS1) relevant for the strength of the CS2 -> CR association?
To make an example: A student gets a bad grade in an exam (CS1) and due to a extremely negative response of his / her parents (screaming, punishment = US) the student develops a fear response to exams in general (single trial fear conditioning; the response "exam -> fear" was learned). Does the student already responds with fear to any stimuli (CS2) which signals a upcoming exam although this association was learned earlier before the fear conditioning? Is it necessary that the association CS2 + CS1 is learned after the CS1 + US association or doesn't it matter?
Explanation of the abbrevations: In classical conditioning a association between an unconditioned stimuli (US) and a conditioned stimuli (CS) is learned so that the person also responds with the response to the conditioned stimuli which he / she has previously shown to the unconditioned stimulus. The classical example is Pavlov's experiment with a dog. A bell was ringing (CS) whenever food was presented to the dog (US). After a while the dog salivates (CR) whenever the bell rings (without presenting the food). Thus the response "bell -> salivation" was learned.
In second order conditioning next to an association of an unconditioned stimulus (US) and a first conditioned stimulus (CS1) also an association of a second conditioned stimulus (CS2) with the first conditioned stimulus (CS1) is learned. Thus the person / the animal also responses with a conditioned response (CR) similar or equal to the unconditioned response (UR) to the second stimulus even though that the association CS2+US was directly presented before.