How does autonomy work in The Sims 4?
Sims 4 autonomy: how Sims choose what to do
A Sim in The Sims 4 scores every action it could do, keeps the 10 best, and picks one at random, weighted by score. Hunger adds nothing until it falls below −25. 2,225 actions also carry fake advertisements: needs they promise but don't fill.
When a Sim is free, The Sims 4 scores every action it could take: how badly the Sim wants each need, how much the action promises to fill it, and how far the Sim must walk. Then it does not simply pick the winner.
The game sorts the options, keeps the 10 best, drops any scored zero or less, and rolls a weighted die. Each option's chance is its score divided by the sum of the scores. That is why a Sim sometimes does the second-best thing, or walks past the fridge.
- 10Options in the final dice roll
- 2,225Actions with a fake advertisement
- 51%Of the top need's desire, to be scored at all
The dice roll, with example scores
| Option | Score | Chance of being picked |
|---|---|---|
| Eat | 60 | 60% |
| Sleep | 30 | 30% |
| Watch TV | 10 | 10% |
How badly a Sim wants each need
| Need | Desire by value | Weight |
|---|---|---|
| Hunger | 100 to -25: 0; -26 to -50: 8; -51 to -75: 64; -76 to -100: 512 to 1,024 | 0.29 |
| Bladder | 100 to -25: 0; -26 to -50: 8; -51 to -75: 128; -76 to -100: 1,024 | 0.05 |
| Energy | 100 to -25: 0; -26 to -50: 8; -51 to -75: 32; -76 to -100: 256 | 2 |
| Hygiene | 100 to -25: 0; -26 to -50: 4 to 8; -50 to -99: 8; -100: 64 | 0.25 |
| Fun | 100 to -25: 1 to 4; -25 to -50: 4 to 8; -50 to -99: 8 to 32; -100: 128 | 1 |
| Social | 100 to -25: 1 to 4; -25 to -50: 4 to 8; -50 to -99: 8 to 32; -100: 128 | 0.5 |
The Glutton trait multiplies the desire for Hunger by 1.5.
Which needs get faked
| Need | Interactions |
|---|---|
| Fun | 587 |
| Hunger | 517 |
| Social | 259 |
| Energy | 48 |
| Bladder | 25 |
| Hygiene | 17 |
14 more use a hidden version. The butler's Make a Snack promises 3.5 Hunger.
Needs only count when they are low
Each need turns its value, from −100 to 100, into a desire through a curve. For Hunger, Bladder, Energy and Hygiene the desire is zero above −25, so a Sim who is only a little hungry doesn't think about food at all.
Below −25 the desire jumps in steps of about eight times. Hunger goes 8, then 64 below −50, then 512 rising to 1,024 below −75. Bladder goes 8, 128, then 1,024. Fun and Social never reach zero, so a bored or lonely Sim always has a small pull toward company.
Each need also has a weight that scales its desire. Energy weighs 2 and Bladder only 0.05, so a full bladder has less pull than its desire suggests. The game only scores the needs whose desire is at least 51% of the top need's.
Fake advertisements
Some actions promise needs they don't fill. The game calls this a false advertisement, and it is only seen by autonomy. We counted 2,225 interactions with one across the base game and the packs. Fun is faked most, then Hunger and Social.
Most are there to make Sims behave. A stove can't feed anyone, the meal does, so starting to cook advertises Hunger to get a hungry Sim to the kitchen. The butler's Make a Snack promises 3.5 Hunger the same way. 14 interactions use a hidden version, such as napping in the bathtub.
How traits change the choice
Personality works by multiplying desires. The Glutton trait multiplies the desire for Hunger by 1.5, so a Glutton picks food more often at the same hunger. Moods and buffs change scores the same way, before the dice roll.
Questions
Why does my Sim not eat when hungry in The Sims 4?
Hunger has no pull at all above −25, and even below it the Sim only rolls a weighted die among its 10 best options. If another need is lower, or the fridge is far away, food can lose the roll a few times before it wins.
Is Sims 4 autonomy random?
Partly. The scores are exact, but the final pick is a weighted random choice among the top 10 options. An option with twice the score is twice as likely, not certain.
What are false advertisements in The Sims 4?
Need scores that an action shows to autonomy but doesn't give. 2,225 interactions have one. They lure Sims into actions that lead to the real reward, like cooking before eating.