Academic journal article Attention, Perception and Psychophysics

Rhesus Macaques (Macaca Mulatta) Exhibit the Decoy Effect in a Perceptual Discrimination Task

Academic journal article Attention, Perception and Psychophysics

Rhesus Macaques (Macaca Mulatta) Exhibit the Decoy Effect in a Perceptual Discrimination Task

Article excerpt

Published online: 2 April 2015

# The Psychonomic Society, Inc. 2015

Abstract The asymmetric dominance effect (or decoy effect) is a form of context-dependent choice bias in which the probability of choosing one of two options is impacted by the introduction of a third option, also known as the decoy. Decoy effects are documented widely within the human consumer choice literature, and even extend to preference testing within nonhuman animals. Here, we extended this line of research to a perceptual discrimination task with rhesus monkeys to determine whether decoy stimuli would impact size judgments of rectangular stimuli. In a computerized task, monkeys attempted to choose the larger of two rectangles that varied in size and orientation (horizontally or vertically oriented). In probe trials, a third stimulus (the decoy) was presented that was smaller than the other two rectangles but matched the orientation of one of them. On half of the probe trials, the presented decoy matched the orientation of the larger stimulus, and on the other half, the decoy matched the orientation of the smaller stimulus. Monkeys rarely selected the decoy stimulus. However, their performance (selection of the largest rectangle) increased relative to the baseline trials (with only two choices) when the decoy was congruent in its orientation with the largest rectangle, but decreased relative to baseline when the decoy was incongruent with the largest rectangle. Thus, a decoy stimulus impacted monkeys' perceptual choice behavior even when it was not a viable choice option itself. These results are explained with regard to comparative evaluation mechanisms.

Keywords Asymmetric dominance effect . Decoy effects . Context effects . Choice behavior . Perceptual discrimination . Rhesus macaque . Macaca mulatta

A homebuyer's realtor has helped her narrow down the many real estate options to two choices. The first home is fully renovated and a half-hour drive from work, whereas the second home is unrenovated but a mere 5-min walk from work. The buyer cannot decide between the two options, since she values both home quality and a short commute time. Her realtor introduces a third option, also known as the decoy-a partially renovated home that boasts a lengthy 1-h commute. Because this option is weaker on both the dimensions of home quality and commute time than the first home, the buyer chooses the first, fully renovated home with the half-hour commute by car. Rational choice theory's condition of regularity states that the relative preferences for the original alternatives within a set should not change with the introduction of a third choice, because each value is made independently of the others (Luce, 1959; Tversky, 1972). However, decisionmaking sometimes is at odds with rational choice theory, and instead, choice behavior may be impacted by context. For the buyer, this so-called decoy option altered her preference for the original two options, such that it increased the preference for the first home that dominated the decoy on both the dimensions of home quality and commute time.

The decoy effect, also known as the asymmetric dominance effect, is a form of context-dependent choice in which the probability of choosing one of two options is impacted by the introduction of a third, weaker option to the choice set (Huber, Payne, & Puto, 1982). In a choice set, the original two options vary on multiple dimensions, such that the first option dominates the second on one dimension, and the second option dominates the first on a separate dimension. The decoy stimulus increases the probability of choosing the original item to which it is most similar. Furthermore, there is a positive correlation between this choice behavior and the similarity of the two items (Huber et al., 1982).

In our example, the first home was stronger in the dimension of home quality, but the second home was stronger in the dimension of commute time. If the homebuyer values both of these dimensions to equal extents, the options are rendered equally attractive, and a decision-maker is indifferent between the two options. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.