Weighing Pros and Cons The study of Shafir (1993):Shafir (1993): Procedure invariance means that two logically equivalent tasks should yield the same outcome in a judgment or decision task. For example, if a jury members are asked to whom of to parents to award child sole-custody, their decision should be same as when asked to whom to deny custody. Shafir (1993) gave his participants the following problem: Contributor© POSbase 2003

Weighing Pros and Cons Imagine that you serve on the jury of an only- child sole-custody case following a relatively messy divorce. The facts of the case are complicated by ambiguous economic, social, and emotional considerations, and you decide to base your decision entirely on the following few observations. © POSbase 2003

Weighing Pros and Cons One group of respondents was asked „To which parent would you award sole custody of the child?“ The other group was asked: „To which parent would you deny sole custody of the child?“ Parent A:average income average health average working hours reasonable rapport with child relatively stable social life Parent B:above-average income minor health problems many working hours excellent rapport with child highly active social life 36% 64% Award 55% 45% Deny © POSbase 2003

Two logically equivalent tasks yielded different choices. If asked to award child custody, respondents based their decisions on salient positive features of the parent; if asked to deny child custody, respondents based their decisions on salient negative features of the parent. Parent B had both salient positive and negative features and was therefore both awarded and denied child custody, depending on the question. Weighing Pros and Cons © POSbase 2003

Weighing Pros and Cons This violates description invariance or procedure invariance, like in studies on compatibility effects (see Slovic & Lichtenstein, 1983; Tversky, Slovic, and Kahneman, 1990), and relative prominence (Kahneman & Ritov, 1993; Tversky, Sattah, & Slovic, 1988).description invariance © POSbase 2003 This is a typical example of a positive test strategy in that people search information that elicits positive responses; these are positive traits if asked to award child custody and negative traits if asked to deny child custody.positive test strategy

Such mechanisms may also play for job decisions: If there are very few open positions, the committee may first ask which applicants to exclude from the list for interviews; according to the logic demonstrated by Shafir, those are excluded with salient negative features, even if these are outweighed by salient positive features. If there are many open positions, the committee may ask first whom they want include for sure into the list. This favors people with salient positive features, even if they are outweighed by salient negative features. Again, the procedure plays a crucial role in decision making. Weighing Pros and Cons © POSbase 2003