I am very grateful that you answered, Iâ€™m sorry that I didnâ€™t answer for a long time, I was busy.

Now I am confused, I observe such an effect as negative activation, my oxyhemoglobin values are negative

Returning to GLM analysis. Yes, I would like to calculate the intergroup contrast for the same conditions, visually displaying it in a clear picture. There are two groups: the first - those who supposedly have abilities in mathematics and the second group - those people who probably have no abilities in mathematics. I am a novice researcher and also sending you the paradigm and montage for this experiment.

**Paradigm**

- Resting state (3 minutes)
- Session 1: consists of three tasks with two-digit numbers, exact calculation (calculation in numerical, calculation in word format, reading. The conditions are not merged, but with randomized order within various respondents, there are 2 levels of difficulty: simple (without carry effect/ without borrow effect); and complex (with carry effect / with borrow effect);

**45 blocks, total duration 36 minutes (20 s interval between blocks):**

**9 conditions * 40 seconds block duration (5 tasks within each block) * 5 block repetitions.**

TASK 1, 20 blocks

*Example: 24+18=*

Condition 1: addition in numerical format, simple (without carry effect)

Condition 2 addition in numerical format, complex (with carry effect)

Condition 3: subtraction in numerical format, simple (without borrow effect)

Condition 4: subtraction in numerical format, complex (with borrow effect)

TASK 2, 20 blocks

*Example: twenty-four plus fifty-five is*

Condition 5: addition in word format, simple (without carry effect)

Condition 6 addition in word format, complex (with carry effect)

Condition 7: subtraction in word format, simple (without borrow effect)

Condition 8: subtraction in word format, complex (with borrow effect)

TASK 3, 5 blocks

*Example: There were 24 apple trees and 13 pears in the garden. How many apple trees were there in the garden?*

Condition 9: Reading

Session 2: consists of exact calculation tasks with two-digit numbers. The conditions are not merged, but with randomized order within various respondents, in each condition there are 2 levels of difficulty: simple (without carry effect/ without borrow effect); and complex (with carry effect / with borrow effect);

**20 blocks, total duration 25 minutes (20 s interval between blocks):**

**4 conditions * 75 seconds block duration (5 tasks within each block) * 5 block repetitions.**

*Example: The boy had 86 dollars, he spent 48 rubles on sweets. How much is left?*

Condition 1: addition in word format, congruent, with and without carry effect

Condition 2: subtraction in word format, congruent, with and without borrow effect

Condition 3 addition in word format, incongruent, with and without carry effect

Condition 4: subtraction in word format, incongruent, with and without borrow effect

My data is in fif format

I can also share my code. How will it be convenient for you to get it?