# Study 2 ## Task data (individual subjects) Data for each participant are in a separate folder, named with their subject ID (e.g. "S01", "S47"). ### Task performance data Each folder should contain multiple `.txt` files, named in the following way: "AB_`SUBJECTID`\_`SESSION` `POLARITY`_`BLOCK`.txt", where: * `SUBJECTID` is the same as the folder name (e.g. "S01", "S47") * `SESSION` is either _1_ (first session) or _2_ (second session) * `POLARITY` is the code for which tDCS polarity was received during this session (_anodal_ or _cathodal_). See `records/tDCS_blinding.md` for the key. * `BLOCK` is whether the data is from the block before tDCS (_pre_), during tDCS (_tDCS_) or after tDCS (_post_). Each file contains a table with the following columns: * __totalTrial__: trial number * __block__: block number * __trial__: trial number within each block (1--39) * __T1pos__: position of T1 in the letter stream (fixed to 5) * __T1letter__: identity of T1 * __T1resp__: participant's response to T1 question * __T2letter__: identity of T2 * __T2resp__: participant's response to T2 question * __T1acc__: 1 if participant was correct (T1letter = T1resp), 0 if incorrect * __T2acc__: 1 if participant was correct (T2letter = T2resp), 0 if incorrect * __T1T2acc__: - 3 = both incorrect: T1 and T2 identities were swapped - 1 = both incorrect: T1 identity given as T2 answer - 2 = both incorrect: T2 identity given as T1 answer - 0 = both incorrect: otherwise - 13 = both correct (no-blink trial) - 11 = only T1 correct (blink trial) - 12 = only T2 correct N.B. Sometimes there are multiple files with the same name, followed by a number (e.g. "AB_S02_2B_tDCS.txt" and "AB_S02_2B_tDCS2.txt"). This was due to a bug that sometimes caused the task program to crash. It would then have to be restarted, creating a new `.txt` file (these are simply concatenated in the data analysis). ### Task log files Each `.txt` file will have its associated `.log` file written automatically by [Presentation](https://www.neurobs.com/presentation), containing info on the stimulus timing among other things. ## Metadata * `subject_info.csv`: table with the following columns: - **subject**: subject ID - **first.session**: Whether subject had anodal stimulation in the first session (_anodal_) or cathodal stimulation in the first session (_cathodal_) - **gender** - **age**: in years ## Questionnaire data * `tdcs_AE.csv`: data from the tDCS side effects questionnaire (see the `records/questionnaires` folder) administered at the end each session. They were asked to which degree the following sensations were present during stimulation: *tingling*, *itching sensation*, *burning sensation*, *pain*, *headache*, *fatigue*, *dizziness* and *nausea*. Each was rated on a scale from 0-4: 1. none 2. a little 3. moderate 4. strong 5. very strong They also rated their confidence *that the sensations were caused by the stimulation* on a scale from 0-4 (columns starting with `conf.`): 1. n/a (meaning they rated the sensation a 0 on the previous scale) 2. unlikely 3. possibly 4. likely 5. very likely Finally, any other remarks participants wrote down are in the *notes* column. # Study 1 ## Task data (summary) `AB-tDCS_study1.txt` is the data from [London & Slagter (2015)](https://doi.org/10.1162/jocn_a_00867) as provided by the lead author. Each row belongs to one subject. Only a subset of the columns are relevant here, with the header structure `block` `stim`\_`target`\_`lag`\_`prime`: * `block` `stim` is either: 1. _vb_: "anodal" tDCS, "pre" block (before tDCS) 2. _tb_: "anodal" tDCS, "tDCS" block (during tDCS) 3. _nb_: "anodal" tDCS, "post" block (after tDCS) 4. _vd_: "cathodal" tDCS, "pre" block (before tDCS) 5. _td_: "cathodal" tDCS, "tDCS" block (during tDCS) 6. _nd_: "cathodal" tDCS, "post" block (after tDCS) * `target` is either: 1. _T1_ (T1 accuracy): proportion of trials in which T1 was identified correctly 2. _T2|T1_ (T2|T1 accuracy): proportion of trials in which T2 was identified correctly, given T1 was identified correctly * `lag` is either: 1. _2_ (lag 2), when T2 followed T1 after 1 distractor 2. _4_ (lag 4), when T2 followed T1 after 3 distractors 3. _10_, (lag 10), when T2 followed T1 after 9 distractors * `prime` is either: 1. _P_ (prime): when the stimulus at lag 2 (in lag 4 or lag 10 trials) had the same identity as T2. Study 2 did not have this condition. 2. _NP_ (no prime) when this was not the case. In addition, __fileno__ is the participant ID and __First_Session__ codes for session order (_1_ meaning participants received anodal tDCS in the first session, _2_ meaning participants received cathodal tDCS in the first session).