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Preferential encoding of behaviorally relevant predictions revealed by EEG.

Stokes MG, Myers NE, Turnbull J, Nobre AC - Front Hum Neurosci (2014)

Bottom Line: In this electroencephalogram (EEG) study, we test how task relevance influences the way predictions are learned from the statistics of visual input, and exploited for behavior.The behavioral results confirmed that participants learned and exploited task-relevant predictions even when not explicitly defined.These results show that task relevance critically influences how the brain extracts predictive structure from the environment, and exploits these regularities for optimized behavior.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Psychology, University of Oxford Oxford, UK ; Oxford Centre for Human Brain Activity, University of Oxford Oxford, UK.

ABSTRACT
Statistical regularities in the environment guide perceptual processing; however, some predictions are bound to be more important than others. In this electroencephalogram (EEG) study, we test how task relevance influences the way predictions are learned from the statistics of visual input, and exploited for behavior. We developed a novel task in which participants are simply instructed to respond to a designated target stimulus embedded in a serial stream of non-target stimuli. Presentation probabilities were manipulated such that a designated target cue stimulus predicted the target onset with 70% validity. We also included a corresponding control contingency: a pre-designated control cue predicted a specific non-target stimulus with 70% validity. Participants were not informed about these contingencies. This design allowed us to examine the neural response to task-relevant predictive (cue) and predicted stimuli (target), relative to task-irrelevant predictive (control cue) and predicted stimuli (control non-target). The behavioral results confirmed that participants learned and exploited task-relevant predictions even when not explicitly defined. The EEG results further showed that target-relevant predictions are coded more strongly than statistically equivalent regularities between non-target stimuli. There was a robust modulation of the response for predicted targets associated with learning, enhancing the response to cued stimuli just after 200 ms post-stimulus in central and posterior electrodes, but no corresponding effects for predicted non-target stimuli. These effects of target prediction were preceded by a sustained frontal negativity following presentation of the predictive cue stimulus. These results show that task relevance critically influences how the brain extracts predictive structure from the environment, and exploits these regularities for optimized behavior.

No MeSH data available.


Related in: MedlinePlus

Task, design and behavioral performance. (A) Participants viewed a stream of fractal images presented at a rate of one per second at the center of the screen. Their task instruction was simply to press the response button after any presentation of a pre-defined target stimulus as quickly as possible. The target was pre-selected randomly for each participant from a set of 10 fractal images. The participant was only instructed to respond to the target, the nine remaining stimuli could effectively be ignored. (B) The presentation probabilities were manipulated. By default, each stimulus was equiprobable, except after a pre-designated target cue (upper) or control cue (lower). These predictive stimuli were followed by the target or control non-target stimulus with 70% validity. On the remaining 30% of trials, stimuli were selected at random from the set of nine remaining stimuli, including the cues and the control or target stimulus. (C) The behavioral response to target stimuli indicated that reaction times were faster for cued targets, relative to uncued targets (main effect: F1,17 = 4.701, p = 0.045, interaction with block: F7,119 = 2.621, p = 0.015). (D) Accuracy was high overall, and was not modulated by cues (p = 0.419).
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Figure 1: Task, design and behavioral performance. (A) Participants viewed a stream of fractal images presented at a rate of one per second at the center of the screen. Their task instruction was simply to press the response button after any presentation of a pre-defined target stimulus as quickly as possible. The target was pre-selected randomly for each participant from a set of 10 fractal images. The participant was only instructed to respond to the target, the nine remaining stimuli could effectively be ignored. (B) The presentation probabilities were manipulated. By default, each stimulus was equiprobable, except after a pre-designated target cue (upper) or control cue (lower). These predictive stimuli were followed by the target or control non-target stimulus with 70% validity. On the remaining 30% of trials, stimuli were selected at random from the set of nine remaining stimuli, including the cues and the control or target stimulus. (C) The behavioral response to target stimuli indicated that reaction times were faster for cued targets, relative to uncued targets (main effect: F1,17 = 4.701, p = 0.045, interaction with block: F7,119 = 2.621, p = 0.015). (D) Accuracy was high overall, and was not modulated by cues (p = 0.419).

Mentions: The task structure is shown in Figure 1, along with stimulus probabilities. Participants were shown a sequence of colored fractal images (50 ms duration, 2.08°× 2.08° visual angle) presented against a gray background (RGB: 127,127,127) and separated by a 1000 ms inter-stimulus-interval. For each participant, one fractal image was randomly assigned as the “target” stimulus and one as the “target cue” stimulus. Another fractal was also selected to serve as the “control” non-target stimulus (i.e., presented with the same probability as the real target), and a fourth stimulus for a “control cue” stimulus (i.e., with the same predictive relationship to the control non-target as the relationship between the target cue and target). The remaining six fractal stimuli served as neutral non-target stimuli. Participants were reminded which was the target stimulus at the beginning of each block, but were not informed about any of the other assignments.


Preferential encoding of behaviorally relevant predictions revealed by EEG.

Stokes MG, Myers NE, Turnbull J, Nobre AC - Front Hum Neurosci (2014)

Task, design and behavioral performance. (A) Participants viewed a stream of fractal images presented at a rate of one per second at the center of the screen. Their task instruction was simply to press the response button after any presentation of a pre-defined target stimulus as quickly as possible. The target was pre-selected randomly for each participant from a set of 10 fractal images. The participant was only instructed to respond to the target, the nine remaining stimuli could effectively be ignored. (B) The presentation probabilities were manipulated. By default, each stimulus was equiprobable, except after a pre-designated target cue (upper) or control cue (lower). These predictive stimuli were followed by the target or control non-target stimulus with 70% validity. On the remaining 30% of trials, stimuli were selected at random from the set of nine remaining stimuli, including the cues and the control or target stimulus. (C) The behavioral response to target stimuli indicated that reaction times were faster for cued targets, relative to uncued targets (main effect: F1,17 = 4.701, p = 0.045, interaction with block: F7,119 = 2.621, p = 0.015). (D) Accuracy was high overall, and was not modulated by cues (p = 0.419).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4151094&req=5

Figure 1: Task, design and behavioral performance. (A) Participants viewed a stream of fractal images presented at a rate of one per second at the center of the screen. Their task instruction was simply to press the response button after any presentation of a pre-defined target stimulus as quickly as possible. The target was pre-selected randomly for each participant from a set of 10 fractal images. The participant was only instructed to respond to the target, the nine remaining stimuli could effectively be ignored. (B) The presentation probabilities were manipulated. By default, each stimulus was equiprobable, except after a pre-designated target cue (upper) or control cue (lower). These predictive stimuli were followed by the target or control non-target stimulus with 70% validity. On the remaining 30% of trials, stimuli were selected at random from the set of nine remaining stimuli, including the cues and the control or target stimulus. (C) The behavioral response to target stimuli indicated that reaction times were faster for cued targets, relative to uncued targets (main effect: F1,17 = 4.701, p = 0.045, interaction with block: F7,119 = 2.621, p = 0.015). (D) Accuracy was high overall, and was not modulated by cues (p = 0.419).
Mentions: The task structure is shown in Figure 1, along with stimulus probabilities. Participants were shown a sequence of colored fractal images (50 ms duration, 2.08°× 2.08° visual angle) presented against a gray background (RGB: 127,127,127) and separated by a 1000 ms inter-stimulus-interval. For each participant, one fractal image was randomly assigned as the “target” stimulus and one as the “target cue” stimulus. Another fractal was also selected to serve as the “control” non-target stimulus (i.e., presented with the same probability as the real target), and a fourth stimulus for a “control cue” stimulus (i.e., with the same predictive relationship to the control non-target as the relationship between the target cue and target). The remaining six fractal stimuli served as neutral non-target stimuli. Participants were reminded which was the target stimulus at the beginning of each block, but were not informed about any of the other assignments.

Bottom Line: In this electroencephalogram (EEG) study, we test how task relevance influences the way predictions are learned from the statistics of visual input, and exploited for behavior.The behavioral results confirmed that participants learned and exploited task-relevant predictions even when not explicitly defined.These results show that task relevance critically influences how the brain extracts predictive structure from the environment, and exploits these regularities for optimized behavior.

View Article: PubMed Central - PubMed

Affiliation: Department of Experimental Psychology, University of Oxford Oxford, UK ; Oxford Centre for Human Brain Activity, University of Oxford Oxford, UK.

ABSTRACT
Statistical regularities in the environment guide perceptual processing; however, some predictions are bound to be more important than others. In this electroencephalogram (EEG) study, we test how task relevance influences the way predictions are learned from the statistics of visual input, and exploited for behavior. We developed a novel task in which participants are simply instructed to respond to a designated target stimulus embedded in a serial stream of non-target stimuli. Presentation probabilities were manipulated such that a designated target cue stimulus predicted the target onset with 70% validity. We also included a corresponding control contingency: a pre-designated control cue predicted a specific non-target stimulus with 70% validity. Participants were not informed about these contingencies. This design allowed us to examine the neural response to task-relevant predictive (cue) and predicted stimuli (target), relative to task-irrelevant predictive (control cue) and predicted stimuli (control non-target). The behavioral results confirmed that participants learned and exploited task-relevant predictions even when not explicitly defined. The EEG results further showed that target-relevant predictions are coded more strongly than statistically equivalent regularities between non-target stimuli. There was a robust modulation of the response for predicted targets associated with learning, enhancing the response to cued stimuli just after 200 ms post-stimulus in central and posterior electrodes, but no corresponding effects for predicted non-target stimuli. These effects of target prediction were preceded by a sustained frontal negativity following presentation of the predictive cue stimulus. These results show that task relevance critically influences how the brain extracts predictive structure from the environment, and exploits these regularities for optimized behavior.

No MeSH data available.


Related in: MedlinePlus