Feature-based Choice and Similarity in Normal-form Games: An Experimental Study. Giovanna Devetag and Sibilla Di Guida “Workshop on Rationality, Heuristics and Motivation in Decision Making” Pisa, November 12-14 2010. Introduction.
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Giovanna Devetag and Sibilla Di Guida
“Workshop on Rationality, Heuristics and Motivation in Decision Making”
Pisa, November 12-14 2010
Our hypothesis is that initial behavior in normal form games relies on simplified/incomplete mental models of the strategic situation and hence can be influenced by a set of features that do not alter a game set of (Nash) equilibria.
The presence vs. absence of these features can also influence the extent to which two games are perceived by players as being similar, regardless of their belonging to the same game-theoretic class.
We chose the following 5 game types:
Features of interest:
What is a Focal Point? relies on simplified/incomplete mental models of the strategic situation and hence can be influenced by a set of features that do not alter a game set of (Nash) equilibria.
Payoff variance as a measure of riskiness
they choose the strategy supporting the focal point (FP)
Hypothesis 1 (relevance of FP) player: For each game type and for each variance level of HA, choices in matrices with FP differ from choices in the corresponding matrices without FP
Hypothesis 2 (relevance of FP and HA over EQ): playerwhen variance of HA is low, strategies FP and HA capture the majority of choices in games with FP, and strategy HA captures the majority of choices in games without FP
Hypothesis 3 (effect of variance): playerKeeping all other features fixed, when the variance of HA increases its share decreases
We identify 4 attributes that may be important in order to increase focality:
Result: the joint presence of payoff magnitude and payoff symmetry determines focality
Hypothesis 5 (Feature-based weak similarity hypothesis) player: a key feature has a similar effect in different game types, by influencing choice behavior in the same direction
For all game types, the difference in choice shares between matrices with and without features is always significant (p<.01)
The presence of a FP and of a “safe” option (HA) influences choices in predictable ways regardless of a game equilibrium properties.
Hypothesis 6 (Feature-based strong similarity hypothesis): playerkeeping all other features fixed, the choice distributions within-feature type are closer - statistically - than the choice distributions within-game type
For game types DomCol, noNE, and UniqueNAsh in the large majority of cases the frequency distributions are indistinguishable among games sharing the same features.
When the game equilibrium structure changes behavior remains invariant.
The distributions of the game types (except for WL and PD) appear significantly different only when all features are removed.
Hypothesis 7 (FP response times): playerthe matrices with FP trigger intuitive reasoning while the matrices without FP trigger analytical reasoning: this difference appears in longer average response times for matrices without FP, ceteris paribus.
Response playertimesas a functionof the varof HA
Infracell payoff experiment (Devetag&Di Guida, in progress)
Own payoff only