Gaze bias both reflects and influences preference S. Shimojo, C. Simion, E. Shimojo, and Scheier 발표 : 생물심리 전공 설선혜

Introduction  Emotions and attitudes have the function of preparing people to act (i.e. approach or aversion) in such a way that the individual need not have much insight into what causes his or her behavior. (Darwin,1872)  The subjective experience of emotions is following facial expression rather than preceding it. (Zanjonc, 1985)  Implicit somatosensory inputs influence emotional and cognitive processes. (Zajonc/ Neumann and Strack, 1999)

Introduction  Orienting behavior is intrinsically linked to emotionally involved processes. (Maner et al., 2002)

Introduction In this study… Orienting behavior  gaze direction Emotionally involved processes  preference decisions The hypothesis is… Gazing has and active role in preference formation and decision makings. Two experiments 1.Two-alternative forced choice task 2.Gaze manipulation

Experiment1: Methods  Two-alternative forced-choice task  Face attractiveness rating (score 1-7)  Eye movement data collection: Video-based eye tracker(30Hz)  All trials were aligned at the moment of response, 1.67s before decision.  The likelihood curve was fitted with a sigmoid function  Main tasks 1) Face-attractive easy (>3.25) 2) Face-attractive difficult (<0.25)  Control tasks 1) Face-roundness task 2) Face-dislike task

Experiment 1: Results Figure 1 A progressive bias in observers’ gaze toward chosen stimulus Face attractiveness - difficult Face-dislike Face-roundnessFace attractiveness - easy Fourier-descriptor-attractiveness

Experiment 1: Results 1.significant difference between the heights of likelihood curves in the main tasks and the control tasks 2.Curves did not reach a saturation level in the main tasks  gaze cascade effect Face attractiveness - difficult Face-dislike Main Face attractiveness - easy Face-roundness Control

Experiment 1: Results  Gaze cascade effect - The gaze bias is continually reinforced when attractiveness comparisons are to be made.  Dual-contribution model

Experiment 1: Results  A larger cascade effect in the difficult task  When the cognitive biases are weak, gaze would contribute more to the decision making. Face attractiveness - difficult Face attractiveness - easy

Experiment 1: Results  Is it evolved from social interaction or basic orienting behavior?  Abstract shape attractiveness task  Basic orienting behavior!  Orienting is essential, particularly when the cognitive systems cannot be discriminative in making preference decisions over a rage of stimuli.

Experiment 1: Results  Is the effect relying on memory?  Two-session face attractiveness task (one-day inter delay) 1 st session 2 nd sessionDecision changed (22.3%)  No!  The cascade effect reflects the process of decision making itself.

Experiment 2: Methods  Gaze manipulation 900ms 300ms 900ms 300ms  Control (central)

Experiment 2: Results  Gaze manipulation, preference 1) Horizontal (2, 6, 12 repetitions) 2) Vertical - to ascertain that saccade size and direction is not important Gaze Manipulation 2 repetition Gaze Manipulation 6 repetitions Gaze Manipulation 16 repetitions Gaze Manipulation vertical No, Central No, Periphera l Gaze Manipulation roundness Percent preference for longer shown face P-value T-test 0.31<0.001*<0.005*<0.0001*

Experiment 2: Results  Control 1) No gaze shift, central (retinotopically identical) 2) No gaze shift, peripheral - to distinguish mere exposure effect from gaze bias Gaze Manipulation 2 repetition Gaze Manipulation 6 repetitions Gaze Manipulation 16 repetitions Gaze Manipulation vertical No, Central No, Peripheral Gaze Manipulation roundness Percent preference for longer shown face P-value T-test 0.31<0.001*<0.005*<0.0001*

Results: Experiment 2  Control 3) Gaze manipulation, roundness - to find out whether specific to preference tasks. Gaze Manipulation 2 repetition Gaze Manipulation 6 repetitions Gaze Manipulation 16 repetitions Gaze Manipulation vertical No, Central No, Peripheral Gaze Manipulation roundness Percent preference for longer shown face P-value T-test 0.31<0.001*<0.005*<0.0001*

Results: Experiment 2 Gaze Manipulation 2 repetition Gaze Manipulation 6 repetitions Gaze Manipulation 16 repetitions Gaze Manipulation vertical No, Central No, Periphera l Gaze Manipulation roundness Percent preference for longer shown face P-value T-test 0.31<0.001*<0.005*<0.0001*  Gaze directly influences preference formation  Table 1 Results of Experiment 2 (gaze manipulation)

Conclusion  Dual-contribution model of preference formation