7 Nudges & Manipulative Techniques Present In Undertale

By Mattia Podini [04.29.21]

In order to successfully engage the audience and deliver the desired aesthetics, games take advantage of specific processes peculiar to the human mind. Influencing the player means keeping control, and the degree of this condition is ultimately decided by designers.

Part of the success of the indie RPG Undertale resides in its skillful control of in-game mechanisms and information. The aim of this article is to present 7 cognitive biases and psychological effects, providing game examples observable inside Toby Fox's most successful videogame.

1. Norm of Reciprocity


People tend to return positive treatments and ignore or repay with hostility negative ones.

This social norm states that we pay back what we received from others, creating a network of obligation. Reciprocity is universal, and stand at the very roots of human society. The social pressure created by this effect can also lead to an unbalanced interaction between the parts: an initial favor can be followed by an action with a bigger positive effect. Moreover the urge to reciprocate decreases over time.

There are three main types of reciprocity:


In the opening segment of Undertale the player can experience this nudge:

The game as a whole subverts the norm of reciprocity with its pacifist ending, and can be seen as a critique of the law of retaliation.

2. Hawthorne Effect


Individuals tend to modify their behavior in response to their awareness of being observed.

Observing or judging human subjects can alter their actions due to the attention they are receiving. The extent of this alteration is linked to the feedbacks received from the observer: explicit intents can lead to a stronger alteration of a subject's behavior.

Three other main factors can arise concurrently with this effect:


After leaving the Ruins the player is observed by a mysterious presence, which will turn out to be Sans the skeleton. Two elements are used to trigger the desired effect:

Characters that break the fourth wall, such as Flowey and Sans, can also modify the behavior of the users, judging their actions.

3. Apophenia


Human tendency to perceive meaningful connections between unrelated things.

It can also be described as "unmotivated seeing of connections accompanied by a specific feeling of abnormal meaningfulness". Apophenia refers to our inclination to see patterns and meaning in random information. This bias can arise from various inputs, especially from complex topics and vague data.

There are four subcategories of apophenia:


W.D. Gaster and the legends created around his figure are a perfect example of this bias:

4. Selective Perception


Individuals tend to perceive specific information based on their particular frame of reference.

People automatically interpret sensory information in a way that is congruent with their beliefs. This tendency is linked to the high number of stimuli experienced by humans, in relation to their needs. Selective perception distorts human judgment, causing an ignorance of opposing viewpoints.


During the course of the story these are some of the elements that tend to be erroneously perceived:

5. Mere Exposure Effect


People tend to develop a preference for things that are more familiar to them than others.

Humans tend to prefer easy cognitive processes over complex ones, for this reason they stick with familiar things. Repeated exposure increases familiarity, and familiarity reduces uncertainty. Ultimately, this phenomenon makes understanding and interpreting easier.


Undyne is introduced to the player through a combination of mere exposure and gradualism:

6. Category Size Bias


The relative size of a category has an effect on its perceived value.

Utilizing this bias, games tend to convey the level of danger that the player is going to face. Incrementing the visual size of an obstacle, in relation to its group, leads to a perceived higher difficulty: for this reason bigger bosses are generally associated to bigger challenges. A visual and numerical categorization can also create a contrast between a minor group, made of bigger and stronger bosses, and a major group of smaller common enemies.


The addressed phenomenon is especially true for the last four main bosses of the neutral run, and it's generally applicable to a selected category of bosses and enemies:

7. Nostalgia Effect


Feelings of nostalgia weaken the desire for money, instead fostering social connectedness.

Nostalgia is an independent emotion, a sentimentality for the past that enhances positive self-regard and provides existential meaning. It has a powerful and long-lasting effect on human decisions. This emotion increases the perception of a social network in which we belong and our urge to spend money.


Undertale posses different elements that can arouse this emotion:

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