People use Facebook to fulfil the need to belong (e.g. connectedness) and the need for self-presentation (e.g. socially desirable profiles). Passive Facebook users experience more loneliness than active Facebook users. Facebook can contribute to feelings of loneliness but this depends on how Facebook is used. Loneliness can decrease following Facebook use if connectedness increases. It can increase following exclusion.

People tend to use Facebook to combat disconnectedness and disconnectedness predicts Facebook use. However, the actual use of Facebook is not related to disconnectedness. This makes Facebook use a cause of connectedness and a consequence of disconnectedness. Disconnectedness is not affected by Facebook use.

Exposure to information about oneself on Facebook leads to an increase in self-esteem. This effect is stronger with more selective self-presentation and compared to exposure to other’s pages. People have a fundamental need to see themselves as good and a threat to this positive self-image leads to attempts of self-confirmation (e.g. by putting self-related information more centrally). Facebook profiles could have a self-confirming influence by providing positive but accurate information about oneself.

A social comparison with idealized online self-presentations is related to decreases in self-esteem. This also depends on whether social networking sites are actively used or passively used. People who spend more time on Facebook have the idea that others are happier. Asynchronicity (1), multiple audiences (2) and audience feedback (3) could increase idealized self-presentation. Individuals with lower self-concept clarity show a larger discrepancy between online and offline self-presentation. It is believed that the digital footprint (e.g. Facebook use) can be used to assess personality.

The perception of a Facebook profile correlates with the actual self-personality traits of a person but not with the ideal-self personality traits. However, not all personality traits are accurately predicted. This might also differ per social media (e.g. Facebook vs. Instagram). The profile is seen as less socially attractive in case of incongruency between other people’s comments and the profile.

People with less self-esteem and less popularity do not succeed in editing their profile in such a way that others see the person as more socially attractive. People take their offline social network with them on online social networking sites. It is difficult to change existing expectations and behaviour patterns due to the identifiability. Outside of social networking sites, it is possible to look for compensation for offline contact.

There are several effects of personality traits on online activity:

• Neuroticism
  This is associated with more internet and Facebook use and there is more idealisation of oneself (i.e. less accurate self-presentation).
• Extraversion
  This is associated with posting more photos, having more friends and using social networking sites as a supplement to offline contacts more than introverts.
• Openness to experience
  This is associated with posting more personal information and an increased likelihood of using blog features.
• Agreeableness
  This is associated with using IM.
• Conscientiousness
  This is associated with using private messages more and making less use of Facebook to what extent they see this as a distraction.

Online use corresponds to offline gender roles. This means that women are more focused on social interaction and maintaining contacts and men are more task-oriented and performance-oriented. Women are more likely to use social networking sites to maintain existing contacts and men are more likely to use social networking sites to make new contacts. The activity on the internet differs but the total time of use does not differ.

The proteus effect refers to adjustments in online self-presentation causing changes in offline self-perception and behaviour (e.g. a taller avatar leads to more assertive behaviour in real-life). The explanation for the proteus effect could be behavioural confirmation (1), the self-perception theory (2), priming (3), social cognitive theory (4), deindividuation (5) and the SIDE theory (6).

The social cognitive theory states that vicarious reinforcement of behaviour of a relevant model (i.e. avatar) leads to changes in the actor. The behavioural confirmation states that people behave according to how they perceive you.

The self-perception theory states that people infer their attitudes from observing themselves as if from third-person perspective. The expectancy violation theory states that non-verbal behaviours that are expected are accepted at face value whereas unexpected behaviours are scrutinized. Expectancy violations may lead to a differential analysis of subsequent behaviour.

The uncertainty reduction theory states that uncertainty is unpleasant and the increase in uncertainty decreases liking. This might mean that anonymous actors might incite less liking. However, uncertainty in pleasurable contexts may prolong positive responses to stimuli. Uncertainty may amplify or prolong the perceiver’s natural response.

Identity replacement refers to the act of substituting another identity for one’s own. Identity misrepresentation refers to the creation of false and misleading impressions about one’s identity. Impostering refers to replacing physical world identities with virtual, avatar-based identities that do not look like them.

The internet allows people to experiment with their identity and it may help people reach their deepest level of individuality (i.e. true self). A very salient group identity may enhance feelings of belonging to a certain group even when the participant is anonymous. The location of the real me determines where people will have more significant social relationships (i.e. online or offline).

The perceived identity can change how a person behaves. The context of communication (1), the degree to which the source is perceived as anonymous (2), the receiver’s desire to identify the source (3) and the receiver’s ability to determine the source’s identity (4) influence a receiver’s attempts at identifying an anonymous other.

Virtual avatars that are more realistic are seen as more trustworthy and credible and this creates expectations that can be violated. Identity misrepresentation is often strongly punished when detected and identity replacement is often punished when it accompanies negative effects. The internet is often used to connect to core group members; people with whom one relates based on their main identity categorization (e.g. nationality).

People who do not suffer from social inhibitions may integrate offline and online worlds and move between them smoothly. The transfer from online to offline may be challenging for socially inhibited people. People who find it easier to build online relationships will strive to move those significant relationships outside of the net to make them a social reality.

There is a lot of uncertainty about privacy in most people. There is uncertainty about which information can be used how and uncertainty about the exact risk of the availability of that information. There is a privacy-service trade-off; a smoother online experience requires giving up some privacy. The privacy-security trade-off states that protection against crimes (e.g. terrorism) requires giving up some privacy.

There is also a lot of uncertainty about the privacy preferences. Confidentiality concerns when asking personal questions can be counter-productive. The privacy paradox states that privacy preferences are a bad predictor of privacy behaviour. People are concerned about privacy but do not do anything to protect it because a discrepancy between attitudes and behaviours (1) and correspondence behavioural attitude depends on contextual factors (e.g. base-line privacy preference).

Privacy preferences are context-dependent. It depends on the default settings (1), the site layout (2), social norms (3) and reciprocity (4). Users can be influenced in their privacy preferences through misleading sites and misleading privacy statements. Context dependence is amplified by uncertainty.

The theory of context integrity states that social expectations affect one’s beliefs regarding what is private and what is public. These expectations vary in different contexts. More control over privacy preferences alleviates privacy concern. Monitoring can induce people to engage in prosocial behaviour or adhere to social norms.

There are different cognitive biases that can explain how privacy preferences are influenced by the design of online technology:

• Anchoring and adjustment
• Framing
• Hyperbolic discounting
• Choice overload

Hyperbolic discounting refers to preferring an immediate reward over long-term privacy risks (e.g. preferring a discount over privacy).

The ability to control risks influences perception of other risks (e.g. more fear of flying than driving). The control paradox refers to the fact that emphasis on control over who information is available to can be at the expense of considerations of what people who receive it can do with it.