The promise of reward changes how we pay attention

Summary: A new study reveals that our brains treat sensitivity and decision bias as separate processes when rewards are at stake. Using eye monitoring and EEG during a visual task, researchers found that the brain regions related to attention increase when we focus on possible rewards, but only when sensitivity increases, not bias.

Surprisingly, the decision bias, our tendency to say “yes” or “not” based on the reward, showed no activity in the centers of care of the brain at all. These findings discover different pathways related to the rewards that shape the way we see and decide.

Key facts:

Divided processing: reward expectations influence sensitivity and bias through separate brain circuits. ATTENTION VERSUS DECISION: Sensitivity involves areas of visual attention; The bias no.

Source: Iisc

Have you ever noticed how animals instinctively choose the most mature fruits of a tree?

This behavior, of looking for the most rewarding option, offers a fascinating vision of the functioning of the brain.

Animals not only focus their attention on the most rewarding objective (the location of the most mature fruit), but also make a quick decision to act on that information. Interestingly, the behavioral and neuronal mechanisms underlying this process are relatively sub -exploited.

Sridharan Devarajan, associated teacher at the Neuroscience Center, the Indian Institute of Sciences (IISC) and his doctoral student Ankita Senguta assumed the task of investigating how the expectation of a reward influences care.

His study in PLOS Biology offers new ideas on this complex process.

Scientists have long known that the promise of a reward guides and dictates behavior. People are faster to detect changes and respond faster and more accurately when they expect a reward.

Many previous studies have investigated how the expectation of a reward influences attention and decision making. But where they fell short, it is differentiating if these processes are governed by the same or different regions and processes in the brain.

To address this gap, Sridharan and Senguta designed an experiment to examine how the expectation of a reward modulates the two key components of attention: sensitivity (the ability to visually identify the most mature fruit) and bias (the decision to act to choose the most mature fruit). Researchers have often fought to disarm the impact of the reward on sensitivity and bias.

The Sridharan team conducted tests with 24 participants, each performing a cognitive task of two parts. The first part tested the effects of reward on sensitivity. The participant looks at a screen that shows two Gabor patches (soft black and white stripes used in care research), one on each side of the screen.

After a brief pause (200 milliseconds), the patches flash, and one (or both) of the patch orientations could change. Participants have to report whether they detected a change in one of the two patches. For each trial that reported precision, they received a monetary reward.

This is where the task became interesting. The researchers strategically manipulated the rewards: the number of reward points was set on one side, while the points varied on the other side; In other words, it could be higher or lower than the fixed side.

Participants would realize this during the task, depending on the points received, which leads them to concentrate and be more sensitive to the thorough changes on the side that would give them greater rewards.

The second part tested the effects of reward on bias. The only difference in this case was that the points to inform a “yes” option (decide occurred a change), in relation to a “no” option (decide that no change occurred) varying on one side; As before, this reward could be higher or lower than the fixed side.

Here, participants would be partial to choose the option yes when it was more rewarding than the SIN option, and vice versa.

During the tasks, the researchers measured the eye movements of the participants and brain activity, and quantified the two attention components.

In the first task, where sensitivity was examined, participants paid more attention and their gaze was attracted to the side associated with greater rewards.

“However, his decisive bias did not change, indicating that only sensitivity was modulated in this task,” explains Sridharan. In addition, well -known cerebral firms, including electrical responses and oscillations, indicated greater sensitivity.

During the second part of the task, where the bias was examined, the researchers observed that the participants were more likely (biased) to choose the option (yes/no) with the greatest expected reward. But during this task, the researchers were surprised to notice that any of the participants’ look or brain patterns coincided with those associated with attention.

“Unexpectedly, changing bias did not result in any specific signature for centers for care in the brain,” says Senguta.

The results of the study show, for the first time, that sensitivity and bias can be governed by separate neuronal mechanisms under the hood, each differently tuned by the anticipation of a reward. In addition, although sensitivity seems closely linked to sensory care centers, bias may be more closely related to brain decision -making centers.

The study also has practical implications to understand how we learn and make decisions in life.

“Studies like ours will help design tasks to understand risk propensions in people, when they face uncertain rewards.

“The findings can help design treatments for addiction behaviors, such as game, which imply a complex reward interaction, attention and impulsive decisions,” adds Sridharan.

About this reward, attention and neuroscience research news

Author: Sridharan Devarajan
Source: Iisc
Contact: Sridharan Devarajan – Iisc
Image: The image is accredited to Neuroscience News

Original research: open access.
“The expectation of reward produces different effects on sensory processing and decision making in the human brain” by Sridharan Devarajan et al. PLOS BIOLOGY

Abstract

The reward expectation produces different effects on sensory processing and decision -making in the human brain

The expectation of reward guides in a robust manner both attention and decisions. However, if common or different mechanisms mediate each of these processes, it is still unknown.

Previous studies have often combined the effect of the expectation of reward on sensory processing and decision -making because the locations selected for sensory prioritization (sensitivity effects) were also prioritized for decisions (criteria effects).

Here, we identify different forms of reward expectation that separately control spatial attention and decision biases in the human cortex.

The sensitivity and criteria were modulated independently when the expected rewards varied between the locations (“specific space”) or the options (“specific to the choice”), respectively. Only sensitivity, not the criteria, the modulations reflected a limited and preserved attention resource.

The established neuronal and physiological care firms, including the gain modulation of potentials related to events, lateralization of alpha band power and oular movement biases, were obtained only by modulation of specific space rewards.

On the contrary, the neural correlates of the decision biases, including the suppression of alpha power prior to the stimulus, selectively accompanied the modulation of reward of specific choice.

Neuronal markers related to attention predicted the modulation of sensitivity due to expectation of specific space reward, but not the modulation of criteria for expectation of specific reward of choice, which indicates its different underlying mechanisms.

Our findings discover behavioral and neural fundamentals fundamentally dissociates of the effects of rewarding in the sensory and decisional selection, with critical implications to understand how reward, attention and choice are related to the human brain.