The following is a list of default (type A) controls:

Video Game Control

Name	Console	Function
Triangle Button	PlayStation 2	Squad-mate menu.
Square Button	PlayStation 2	Use item.
Circle Button	PlayStation 2	Interact.
X Button	PlayStation 2	Fire Weapon.
Left Directional Button	PlayStation 2	Next item.
Right Directional Button	PlayStation 2	Previous item.
Up Directional Button	PlayStation 2	Previous weapon.
Down Directional Button	PlayStation 2	Next weapon.
Left Analog Stick	PlayStation 2	Move.
Right Analog Stick	PlayStation 2	Zoom.
L1 Button	PlayStation 2	Weapon and items inventory.
L2 Button	PlayStation 2	Sidestep left.
L3 Button	PlayStation 2	Crouch.
R1 Button	PlayStation 2	Free-look.
R2 Button	PlayStation 2	Sidestep right.
R3 Button	PlayStation 2	Reload current weapon.
Select Button	PlayStation 2	Documents and keys inventory.
Start Button	PlayStation 2	Pause menu.

based

1. The official The Thing instruction booklet (PlayStation 2 version).