Multiphasic Value Biases: Raw EEG Data

Raw EEG data from paper: <br> Corbett, Martinez-Rodriguez, Judd, O'Connell &amp; Kelly (2022), Multiphasic Value Biases in Fast-Paced Decisions. <br> Perceptual decisions are biased toward higher-value options when overall gains can be improved. When stimuli demand immediate reactions, the neurophysiological decision process dynamically evolves through distinct phases of growing anticipation, detection and discrimination, but how value biases are exerted through these phases remains unknown. Here, 17 participants performed a motion direction discrimination task under high speed pressure, in which one alternative was more valuable than the other. By parsing motor preparation dynamics in human electrophysiology, we uncovered a multiphasic pattern of countervailing biases operating in speeded decisions. Anticipatory preparation of higher-value actions began earlier, conferring a “starting point”-advantage at stimulus onset, but the delayed preparation of lower-value actions was steeper, conferring a value-opposed buildup rate bias. This, in turn, was countered by a transient deflection toward the higher value action evoked by stimulus detection. <br> Raw 128 channel EEG (Biosemi BDF files). 8 external channels: 1- Above left eye 2- Below left eye 3- Left mastoid 4- Right mastoid 5- Left thumb EMG distal 6- Left thumb EMG proximal 7- Right thumb EMG distal 8- Right thumb EMG proximal <br> Naming convention: ParticipantRegimeBlockNo.bdf or Participant_RegimeBlockNo.bdf <br> e.g. P1_H1.bdf or P29L2.bdf <br> Regimes: H: High coherence blocked. L: Low coherence blocked. I (or HL for P1): Interleaved. <br> Files with N in the filename are 'neutral' practice blocks with no value bias (not used in the analyses). <br> Note P22 had 2 sessions for the H and L regimes. The second of these sessions has the naming format: <br> P22Regime3BlockNo.bdf, <br> where the '3' denotes session 3. <br> Task code (MATLAB/Psychtoolbox) available with the behavioural dataset. <br> Event trigger descriptions: <br> StartTask = 1 Fixation on = 4; Cue on = [8 9 7]; % [high-on-left, high-on-right, neutral] Dots on = [24 25]; % [dots left dots right] Response = [20 21]; % [left-button right-button]

本原始脑电图（Electroencephalogram, EEG）数据集源自以下论文：Corbett、Martinez-Rodriguez、Judd、O'Connell及Kelly（2022）所著《快速决策中的多相价值偏差》（Multiphasic Value Biases in Fast-Paced Decisions）。

当整体收益可得到提升时，知觉决策会偏向高价值选项。当刺激要求被试做出即时反应时，神经生理层面的决策过程会历经逐步发展的三个阶段：期待萌发、刺激检测与辨别区分，但价值偏差如何通过这些阶段发挥调控作用仍未明确。本研究中，17名被试在高速反应压力下完成一项运动方向辨别任务，任务中其中一个选择项的价值高于另一项。通过解析人类脑电记录中的运动准备动力学特征，我们揭示了快速决策中存在一对相互制衡的多相偏差模式：高价值动作的预期准备启动更早，在刺激呈现时便具备了“起始点”优势；而低价值动作的准备过程虽延迟，但累积速率更陡峭，形成了与价值取向相悖的累积速率偏差。这一偏差又会被刺激检测阶段所诱发的、朝向高价值动作的瞬态电位偏转所抵消。

本数据集包含原始128通道脑电图（EEG）数据，存储格式为Biosemi BDF文件。额外附带8个外置通道：1. 左眼上方；2. 左眼下方；3. 左乳突；4. 右乳突；5. 左拇指远端肌电（Electromyography, EMG）；6. 左拇指近端肌电；7. 右拇指远端肌电；8. 右拇指近端肌电。

文件命名可采用两种格式：ParticipantRegimeBlockNo.bdf 或 Participant_RegimeBlockNo.bdf。示例如下：P1_H1.bdf 或 P29L2.bdf。

组别定义：H代表高一致性组块设计；L代表低一致性组块设计；I（P1采用HL标记）为混合组块设计。文件名中包含N的为中性练习组块，无价值偏差设置，未纳入后续分析。

注：被试P22的H与L组别包含2次实验会话，第二次实验会话的命名格式为：P22Regime3BlockNo.bdf，其中数字“3”代表第3次实验会话。

基于MATLAB与Psychtoolbox开发的任务代码可随行为数据集一同获取。

事件触发器说明如下：
StartTask = 1；Fixation on = 4；
Cue on = [8 9 7]; % [高价值选项在左侧、高价值选项在右侧、中性条件]
Dots on = [24 25]; % [左侧运动点、右侧运动点]
Response = [20 21]; % [左键响应、右键响应]