No abstract

In studies on avoidance learning, a warning signal is followed by an aversive unconditioned stimulus unless the participant performs a designated response. The authors examined whether avoidance behavior can be based on hierarchical knowledge, that is, knowledge about the conditions under which certain relations hold. In the present study, a single avoidance response had different effects depending on the nature of the warning signal. Results showed that participants acquired this hierarchical knowledge and used it to avoid negative outcomes. The results are in line with an occasion setting account of avoidance learning and can be explained also by a modified version of Lovibond's (2006) account of avoidance learning.

No abstract

290Avoidance behavior is an instrumental response that prevents the occurrence of an aversive event. It is a common phenomenon in life, since a great deal of our activity is performed to avoid the occurrence of negative or aversive stimuli. In a typical study of avoidance learning, a warning signal (A) is presented and followed by an aversive unconditioned stimulus (US), unless the participant performs a designated response (R). For example, a tone (A) is presented and is followed by an electric shock (US), unless the participant presses a certain key (R). Recently, a new theoretical approach was proposed by De Houwer, Crombez, and Baeyens (2005; see Gray, 1987;Lovibond, 2006;Mowrer, 1947;and Seligman & Johnston, 1973, for other accounts of avoidance learning). Their cognitive theory was based on the observation that avoidance behavior and negative occasion setting are quite similar at the structural level (for a review on the literature of occasion setting, see Holland, 1992, or Schmajuk & Holland, 1998. In negative occasion setting, the occasion setter signals whether a certain stimulus (also called the target) will be followed by the US. If the occasion setter is presented together with the target, the US will not follow, but it will if the occasion setter is not presented. Avoidance behavior, in its turn, also involves a feature negative discrimination: If the avoidance response is performed, the warning signal will not be followed by the US, but it will be if the avoidance response is not performed. From this structural perspective, avoidance learning and negative occasion setting are similar. The only difference is that in the former the occasion setter is a behavior, whereas in the latter the occasion setter is a stimulus (e.g., a tone).De Houwer et al. (2005) investigated whether avoidance behavior is similar to negative occasion setting at a functional level as well. According to Holland (1992), an occasion setter possesses three properties. First of all, it modulates responding to the target. In the case of negative occasion setting, the participants learn that the presence of the US after the presentation of the target is less probable when the occasion setter is presented, whereas the absence of the occasion setter indicates that the US will be presented after the target. This implies that conditioned responding to the target will be stronger when the occasion setter is absent than when it is present. Whereas the property of modulation is not unique to occasion setters (e.g., even presenting a novel stimulus together with a target can modulate responding to the target), the other two properties are. The first of these unique properties is that a negative occasion setter modulates responding to the target independent of its own relation with the US. This means that even when there is a positive contingency between the negative occasion setter and the US, this contingency has no effect on the modulation of the negative occasion setter. In the literature, this property is called resistance against coun...

In most studies on avoidance learning, participants receive an aversive unconditioned stimulus after a warning signal is presented, unless the participant performs a particular response. Lovibond (2006) recently proposed a cognitive theory of avoidance learning, according to which avoidance behaviour is a function of both Pavlovian and instrumental conditioning. In line with this theory, we found that avoidance behaviour was based on an integration of acquired knowledge about, on the one hand, the relation between stimuli and, on the other hand, the relation between behaviour and stimuli.