# Gerry's World

A glimpse into my life

October 14, 2023

## Intro

Nobel Prize in Economics awardee Daniel Kahneman has written several books / papers that mention an “Add-1” mental exercise to study our “System 1” (autonomic) vs “System 2” (deliberate) thinking. I wanted to try it out for myself, so I made this online demo. Consider checking out Ch. 2 of his book Thinking Fast and Slow for more details.

Here’s a video of me trying it out (Add-3 variant):

## Instructions

The task is described (among other places), on Page 23 of the book Attention and Effort:

• There’s 2 options: listen-think-say, or listen-say-say
• During the entire test, record pupil size and watch as it changes size. Pupil size is an easily measurable response to mental effort.
• The procedure is as follows:
2. [2s] Rest
3. [4s] Listen: “Hear”1 a 4-digit number one digit per second
4. [1s] Rest
5. [4s] Think or Say the number, except add 1 to each digit, e.g. 1234 -> 2345, or 7932->8043
6. [1s] Rest
7. [4s] Say the add-1 number (again if you already said it once)

Visual depiction of the procedure1:

Rest
Hear a 4-digit number
Rest
Think or Say the number
Rest
0s
1s
2s
3s
4s
5s
6s
7s
8s
9s
10s
11s
12s
13s
14s
15s
16s
17s
18s

## Demo

#### Demo Options

• Recording: You may enable webcam recording so that you can go back and watch (and download) a video of your pupils. You may want to get really close to the screen and shine a flashlight at your eyes if you have dark colored eyes.
• Task selection: Although the results (pg 23) were stated that it didn’t make much difference whether the middle item was to “think” or “say” compared to the overall task difficulty, I still give the option to let the computer randomly select which one you should do, as in the experiment. This only changes the text displayed but not the behavior.
• Variant Selection: You can try 3 variants:
1. Repeat the same number
2. Add-1: Add 1 to each digit (e.g. 1234 -> 2345 or 7932 -> 8043)
3. Add-3: Add 3 to each digit (e.g. 1234 -> 4567 or 7932 -> 0265)

This only changes the text displayed but not the behavior.