In decision making, your perception is influenced by judgments you have made in the past as a way of remaining consistent with yourself, new research from the University of Pennsylvania suggests.
The findings give us greater understanding of human decision making generally, and open a window into further investigation of how our choices are affected by our attempts to be self-consistent.
We make thousands of decisions every day based on sensory information - where to walk, who to greet and what to eat. How such perceptual decisions are formed through the integration and evaluation of sensory evidence has been studied extensively.
But while previous research has suggested that the choices we make may influence our subsequent decisions, the findings have been diverse, and there is no clear model explanation that connects the various results.
Influences On Decisions
To address this, researchers Long Luu and Alan A Stocker tested the hypothesis that attempting to remain self-consistent leads to post-decision biases in people when making future choices.
“We expressed this hypothesis with a self-consistent Bayesian model, which assumes that a person’s perception is influenced by both their sensory evidence and their earlier choices when making a decision,"
explained senior author Alan Stocker, Associate Professor at the Computational Perception and Cognition (CPC) Laboratory, University of Pennsylvania.
[caption id=“attachment_95683” align=“aligncenter” width=“680”] Post-decision biases in a perceptual task sequence.
(a) Perceptual decision-making in a discrimination-estimation task sequence: Does a discrimination judgment causally affect a subject’s subsequent perceptual estimate?
(b) Experiment 1: After being presented with an orientation stimulus (array of lines), subjects first decided whether the overall array orientation was clockwise (cw) or counter-clockwise (ccw) of a discrimination boundary, and then had to estimate the actual orientation by adjusting a reference line with a joystick. Different stimulus noise levels were established by changing the orientation variance in the array stimulus.
(c) Psychometric functions and estimation biases (combined subject). Estimation biases are only shown for correct trials and are combined across cw and ccw directions. Subjects show larger repulsive biases the noisier the stimulus and the closer the stimulus orientation was to the boundary.
(d) Distributions of estimates for the three stimulus noise levels tested, plotted as a function of stimulus orientation relative to the discrimination boundary (combined subject). Estimates are clearly biased away from the discrimination boundary forming a characteristic bimodal pattern.
Credit: Long Luu, Alan A Stocker CC-BY[/caption]
The scientists validated their newly developed model and its key assumptions with a set of three psychophysical experiments carried out by 10 participants (six males and four females). These experiments focused on a task sequence where the subjects first had to judge whether the overall orientation of a visual pattern (the stimulus) was clockwise or counterclockwise of a reference, before recalling the actual orientation of the pattern from memory.
The second experiment tested how the subjects' orientation estimates were dependent on their knowledge of the stimulus in the first test, while the third experiment looked at whether they treated their judgments as if they were correct.
A new set of study participants, in addition to the original 10, were recruited to perform the second and third experiments.
“Our tests validated the self-consistent model by showing that the bias pattern depended on the subjects' prior knowledge of the stimulus, and that the subjects treated their decision as if it were absolutely correct. Together, the results suggest that our decisions can substantially change our immediate memory of what we have just perceptually experienced in an attempt to make our experience consistent with our preceding decisions,"
said first author Long Luu.
Luu, graduate student in the CPC Laboratory at the University of Pennsylvania, added that the current model links to well-known cognitive phenomena such as confirmation bias and suggests that, in decision making generally, the brain focuses more on remaining self-consistent than on remembering precise details of the past.
“This indicates that humans subconsciously condition themselves to be self-consistent in how they remember the past, and our model allows us to precisely quantify and predict these bias effects,"
The work was supported by the National Science Foundation.
Long Luu, Alan A Stocker Post-decision biases reveal a self-consistency principle in perceptual inference eLife 2018;7:e33334 DOI: 10.7554/eLife.33334
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