Influencing Factors Affecting Young People’s Attitude Towards Online Advertising: A Systematic Literature Review

Young people are constantly targeted by online advertisements. This systematic literature review aims to identify the principal factors that influence young people’s attitude towards online advertising. It seeks to understand if the influence of online advertising is dependent on gender and age differences in young people. The methodology involves the systematic review of empirical studies published from 1994 to 2020 and identifies the factors that impact young people’s attitude towards online advertising. The review commences with a scoping study and follows the PRISMA structure, which includes identifying studies, screening and evaluation, the analysis and synthesis of studies, and the presentation of the final studies. This work reveals two main observations from a thematic content analysis of the appraised studies. The first relates to the principal factors influencing young people’s attitude towards advertising. These factors comprise informativeness, entertainment, irritation, credibility, personalisation, and interactivity. In general, studies show that when informativeness, entertainment, credibility and interactivity are present, the more positive the attitude towards advertising is, while irritation fosters an unfavourable attitude. Studies provide a dichotomous stand on personalisation. The second relates to young people’s age and gender. Our review notes that earlier studies lack focus on audiences predominantly between 10 and 15 years.


1.INTRODUCTION
Young people total more than 1.8 billion, or 23.7 per cent of the world's population (UNFPA, 2020). Eurostat (2020) revealed that almost 94 per cent of young people in Europe surf the Internet daily. In this light, young people have become an important audience for many online advertisers (Bitner and Albinsson, 2017). Indeed, adolescents are now the primary target of today's robust and personalised online advertising (Cardoso and Cardoso, 2012). Technology allows advertisers to change course from traditional mass advertising to more direct and personalised marketing, delivering more accurate and customised advertising that suits individual needs (Baek and Morimoto, 2012). Advertisers can reach and influence many target users at a significantly lower marketing cost, making this tool one of the most powerful and persuasive of all forms (Kafka and Molla, 2017). Internet accessibility has made online advertising a vital tool for many marketers to generate awareness, instil desire, provide information, and influence customer attitudes (Duffett, 2017). Online advertising involves many types of marketing messages shown by or on the Internet, via a search engine, on social media sites, websites, mobile devices, or email, among others. Nonetheless, the traditional media platforms used for advertisement by marketers have shifted mainly to social media (Lee and Hong, 2016). Research progressed at a rapid pace in this area; it has moved from conventional marketing methods to online strategies. One aspect which studies focused on is the individual's attitudes towards advertising.
adds that this tendency of favourite and unfavourite manner can be attributed to advertising in general. Schlosser et al. (1999) state that consumer attitudes towards advertising play a crucial role as they "likely influence consumers' exposure, attention, and reaction to individual advertisements" (p.35).
We analyse the factors that influence young people's attitude towards online advertising by reviewing earlier published studies. Indeed, our study seeks to answer two research questions: RQ1: Which are the principal factors that influence young people's attitude towards online advertising? RQ2: How do these influencing factors affect the attitude of young people towards online advertising?

2.THEORETICAL BACKGROUND
In addressing our research questions, we started with a scoping study that helped us build reliable search strings for use in our systematic review based upon an outline of a broad subject (Peterson et al., 2017). During our scoping study, we explored literature that informed us of online advertising characteristics, the nature of retargeting, young audiences, attitude towards advertising, and the value of advertising. Following this, the factors were explored, and principal constructs were defined.

Online Advertising
The first web banner advertisement featured on HotWired.com in October 1994 (Adams, 1995). It was the starting point of a vital marketing tool -online advertising, which in turn, expressively expands and enhances the perception and vision of a product (or brand) with a strong, positive impact on sales (Ahmed et al., 2019). Goldfarb (2014) classifies online advertising into three groups, comprising search, classified and display advertising. Search advertising is the one that appears on the screen when an individual searches for something on a search engine. Classified advertising runs on web pages that do not have other "media content or an algorithmic search" (Goldfarb, 2014, p.117). Display advertising does not pertain to search engines, taking the form of banner advertisements and social media advertisements, for example.
Internet convenience aided online advertising to be an essential medium for advertisers to create awareness, generating enough interest, and impact customer attitudes (Ariffin et al., 2018). Online advertising is different from any other form of advertisement due to its flexibility and targetability (Sajjacholapunt and Ball, 2014). Nevertheless, if an online advertisement does not grasp the Internet user's attention, it will instil an unfavourable attitude towards it, with an ineffective effort to raise awareness and shape consumers' perception (Maughan et al., 2007). Online advertising reaches out to existing consumers, forms new ones by locating them and offers information and insights to channel advertisers to acquire more knowledge and expand their customer base (Ariffin et al., 2018).
Being an incremental innovation of traditional advertising, retargeting exposes online audiences to repeated online advertisements that users would have seen online in earlier searches or encountered while visiting a website (Goldfarb, 2014). Retargeting is an enhancement of online advertising. When users show interest by visiting a website or enabling a video, a tracking cookie embeds on the browser of the device being used, and it tracks the user's behavioural trail and sites accessed after that. Repeated advertising exposure is believed to distribute the correct personalised messages sent by the advertiser to the right individual at the appropriate time, implicating that people perceive it as more relevant and consistent with their goals and interests (Cho and Cheon, 2004).

Young People and the Online Environment
UNICEF (2019) declares that adolescents are individuals between 10 and 19 years, while teenagers are individuals between 13 and 19 years. The United Nations (UN) (2013) also recognises that different countries or groups (e.g. The African Youth Charter) consider youths in different age groups, even up to 35 years. The World Health Organisation (WHO, 2019) interpret youths as individuals with ages from 15 to 24 years, and young people are aged between 10 and 24 years, combining adolescents and youths. Hence, this study used "young people" as an umbrella term to collect all the keywords that identify individuals from 10 to 24 years.
Young people's judgemental and rational abilities would be still at a development stage, with their capability to discern and assess the advertising techniques and persuasion strategies not fully matured (Zarouali et al., 2016). Indeed, maturity plays an essential role in the influence, effect, and impact of advertisements on teens (Kuppuswamy and Narayan, 2010) and the online environment. The online environment, predominantly social media sites, provide an integral aura where young people can express themselves and relish their attitudes (Steeves and Regan, 2014). More negative effects can entrench young people and put them in a vulnerable position (Kuppuswamy and Narayan, 2010), as Generation Z youths are the internet generation, and they are getting information and news primarily from the web. An adolescent watching an advertisement on TV can take it passively and uses zipping and zapping capabilities to overcome such infiltration. However, young people can be immersed in a fully branded Internet atmosphere for an extended period of time, with the fine line between real content and advertising becoming blurry (Cai and Zhao, 2013). Websites and social media sites are inundated with advertisements; hence young people are coming across these advertisements every minute of online usage. Young people are the early adopters of new media technology and are being targeted aggressively by advertisers using "specialised marketing" techniques (Story andFrench, 2004, as cited in Cardoso andCardoso, 2012, p.23). Young people are living in an online environment for several hours, with Brunborg and Burdzovic Andreas (2019) suggesting that they spend an average of two and half hours daily on social media sites.

Attitude Towards Advertising
Attitude towards advertising is very sensitive and need to be appropriately nourished as 97 per cent of consumers surf over the Internet to collect information so they can form their judgement and decide on their evoked set (Knight, 2010). Several studies were conducted to understand the attitude towards advertising (e.g. Mehta, 2000). MacKenzie and Lutz (1989) suggest that the attitude towards advertising employs a significant influence, along with numerous variables. Fishbein and Ajzen (1975) developed the Theory of Reasoned Action (TRA), where this theory predicts that behavioural intent is formed by an individual's attitudes, opinions, and subjective norms. An extension to TRA, the Theory of Planned Behaviour (TPB) added the perceived behavioural control to the original model (Ajzen, 1991). Likewise, another influential model created by Davis et al. (1989), the Technology Acceptance Model (TAM), predicts that an individual's ability is based upon the acceptance of the technology. The five major constructs of TAM are attitude, intention, use, and ease of use, and perceived usefulness. Hence, both TAM and TPB acknowledge that ultimately, attitudes form intentions, and intentions shape the buying behaviour. The attitude towards advertisement regulates the efficiency and effectiveness of advertising, the purchase intent and attitude towards the brand (MacKenzie and Lutz, 1989).
Attitude employs a significant stimulus along with four variables -credibility, perception, attitude towards the advertiser and mood (MacKenzie and Lutz, 1989). These models and concepts have been related to online advertising, mainly social media (e.g. Kim and Han, 2014). The significance of the attitude towards online advertising has been proved several times by different researchers when they found that it positively influences product and brand, ultimately impacting the purchase intent (e.g. Kola and Akinyele, 2010).
In 1993, Pollay and Mittal constructed the Belief Factor Model in which they factorised seven beliefs that drive attitudes. These beliefs were grouped according to personal utility and the socio-economic effects. The personal utility is made up of "product information", "social-image information", and "hedonic amusement", while the socio-economic effects comprise of "good for the economy", "fostering materialism", "value corruption", and "falsity/no-sense" (Pollay and Mittal, 1993, p.99). Nonetheless, some factors which Pollay and Mittal (1993) worked upon, as most of the socio-economic effects are "predictive tools for the future" (Laforet and Limahelu, 2009, p.168), and can be difficult for the collection of information.

Advertising Value
Two years after Pollay and Mittal (1993) model, Ducoffe (1995) formulated the three starting-point factors defining how consumers value advertising and form an attitude towards an advertisement. The three constructs are informativeness, irritation, and entertainment. His study came amidst a wave of negative articles placing advertising in a bad light (e.g. Alwitt and Prabhaker, 1992). Ducoffe (1996) states that if an advertisement features when the consumer does not need a product, it would be a wasted advertisement. Ducoffe's (1995) initial idea was to turn the advertising tool into one which is worth and can be utilised by the consumer; Advertising value is a measure for advertising effectiveness and the attitude towards advertising, and "may serve as an index of customer satisfaction with the communication products of organisations" (p.1). Ducoffe constructed his model on the Uses and Gratifications Theory (UGT). UGT is an approach to understand mass communication and places the individual in the spotlight rather than the media. Hence it is what an individual does to the media rather than the contrary (Katz, 1959). In this model, the cognitive, affective, personal, and social needs are the uses and gratifications factors. Established on this, Ducoffe (1995) formed the Advertising Value Model by placing informativeness under the cognitive group and irritation and entertainment constructs under the affective category. Hence, based on the notion coined by Houston and Gassenheimer (1987), the idea of value in marketing is constructed on the premise that something worth and valuable can be exchanged between two entities. It is derived from the belief and perception formed about the offering, based upon the experiences that accompany the exchange and behavioural engagement to acquire the exchange (Ducoffe, 1996). Informativeness and entertainment can aid consumers' attitudes towards advertisement to drive them to instil the desire and ultimately purchase, while irritation can enact adverse effects.

3.RESEARCH METHODOLOGY
In our systematic literature review, we follow the PRISMA structure as a guideline to ensure that our review is conducted with rigour, a systematic and reproducible approach is adopted, and transparency and freedom of bias are guaranteed (Moher et al., 2009). A PRISMA flow-chart ( Figure 1) plots the identification, screening, eligibility, and inclusion stages.
The review involved five stages. First, a scoping study helped to outline the research area of study, identify the overarching research question, classify the keywords that could be associated with this study, and develop basic categories and an analysis structure. From the outset, we noted that different scholars focused their study on online advertising in general.
The second stage involved identifying works eligible for this review. We collected the articles for this study from academic journals starting from January 1994 until December 2020. The articles were collected from 1994, since the first online advertisement was featured on the Internet in October 1994. The period was long enough to identify changes and observe any paradigm shifts from the outset until the time of writing. We used an open-string policy to capture all papers and minimise the risk of leaving anything out. When the search was tested using the main words in the research question -'attitude', 'advertising' and 'adolescents', the results indicated that many papers had been omitted due to either non-detection of words or based on different topics.
As Webster and Watson (2002)  adolescent OR adolescents OR teen OR teens OR teenager OR teenagers OR "young adult" OR "young adults" OR "young people" were used as constant variables, and then shifted only the other keywords, using "retargeting", "retargeted", "remarketing", and all the derivations of the following: "optimised advertising", "advertising optimisation", "repeated advertisement", "internet advertisement", "digital advertisement", "digital marketing", "online advertising", "online marketing", "social media  Moher et al., 2009) advertising", "social network advertising". The terms "young adult/s" were included in the string after a test was conducted without the term during the scoping phase and resulted in very few results. This could have hindered the scope of the study and render it impractical. Twenty-two additional records were identified, using scholar.google.com, academia.edu and researchgate.net; all three websites were set with an online prompter, and when a paper of high interest was uploaded or published in any of these respective databases, a notification was received.
The third stage involved all the articles being uploaded on Rayyan QCRI (Qatar Computing Research Institute) system designed by Mourad et al. (2016). Initially, titles of articles and abstracts of studies located through the literature searches were screened. This was a large task, with 16,298 articles and 22 articles from other sources, out of which more than 23 per cent were duplicates. When wrong study area papers were omitted, 501 articles were identified for eligibility screening in relation to the study (Figure 1).
The fourth stage included the laborious screening of all the 501 articles, which were read and scrutinised individually. Out of these articles, 468 were excluded. The exclusion criteria included all those articles that were not directly in the scope of the study (n = 367), book chapters or reviews (n = 14), conference papers (n = 6), editorial columns (n = 7), and papers which were exclusively children-related (n = 9).
Studies that focused on adults (n = 18) were excluded and so did to literature reviews and meta-analysis (n = 14) and methodologicalbased articles (n = 19). Papers with no methodology or no data collection included (n = 2), and no indication of journal or publisher (n = 2) were also excluded. Two (n = 2) papers were omitted as the researchers did not reply with submitting their work for analysis, and these could not be obtained after multiple attempts. Finally, eight (n = 8) papers were excluded from the list as the studies focused on other platforms, such as SMS, TV, and in-app advertisement.
Thirty-three studies met the inclusion criteria and were involved in the analysis and synthesis phase (Table 1). Ducoffe's (1995) advertising value model was used as the theoretical foundation, and all studies were chosen with at least two factors for comparison purposes. It is to be noted that ages that surpassed the 10-24-year bracket were included on the premise that they would account for more than 60 per cent of the whole study and not older than 35 years as per UN (2013) decisions. All the papers were scrutinised using Mendeley software v1.19.

Data Extraction and Synthesis
An integral part of the process was the data extraction process, the synthesis of all the included papers, and the systematic literature review writing phase. The fifth and final phase was conducted using the qualitative analytical instrument NVivo v.12, in which all studies were carefully allotted in folders for segregation and individually tagged for double-checking purposes. Although the initial target date for the collection of data was from 1994, the first valid study retrieved was in 1995. The papers included in the synthesis were extracted from 26 different journals, with four journals having two papers each and one journal has four peer-reviewed studies. As expected, the journals pertain to different disciplines since the study is multidisciplinary and subsets marketing, psychology, computer sciences, and social behaviour ( Table 2). The journals included in this study ranged from the International Review of Management and Marketing to Computers in Human Behaviour Journal. The inclusion phase used articles from Sustainability, Social Behaviour and Personality, Vision, and an English-written study from a Portuguese journal.
All the studies were scrutinised meticulously. The included studies were conducted worldwide ( Figure 2), with the majority, 45 per cent of the studies conducted in Asia and 18 per cent in North America. Europe had only three exclusive studies. There were two studies conducted with African consumers and two with South American consumers. There were five studies which were conducted transnationally, with four studies involving two continents; a study held in Asia and North America (An and Kim, 2007), another one in Europe and North America (van der Goot et al., 2018); and two in Asia and Europe (Wang and Sun, 2010;Deraz, 2019). Another study was conducted in Asia but across India, South Korea, and China (Islam, 2017).
In general, two perspectives were identified. They were categorised as studies focusing on a) the attitude towards advertisements based on different streaks of online marketing, such as online advertising (e.g. Ching et al., 2013), social media advertising (e.g. Saxena and Khanna, 2013), and email advertising (e.g. Baek and Morimoto, 2012), with the influences that affect it (Ariffin et al., 2018) and b) the comparison of attitude towards advertisement between different cultures (e.g. Islam, 2017), media (e.g. Logan et al., 2012), and generations (e.g. van der Goot et al., 2018).

DISCUSSION OF RESULTS
Following a thematic content analysis of the papers and the key topics discussed in the theoretical background, two main themes emerged: (1) the principal factors affecting attitude, and (2) how young people are affected based on their age and gender.

Principal Factors Affecting Attitude
Six principal factors were identified as the most influential among young people, affecting their attitudes towards online advertising. Moreover, these factors were present in the different studies that were chosen. Informativeness appeared in 31 studies, while entertainment was involved in 32 studies out of 33. Twenty-four papers included irritation, whereas credibility or trust was used in 20 studies. Personalisation and interactivity appeared in five studies each. Different researchers mentioned other factors but were not included with the principal factors either because they were chosen by few or deemed not effective. Table 3 provides a whole list of the implications from the studies as per their respective authors. Ducoffe (1996) defines informativeness as the 'content' part of the advertisement, which is an essential determinant of advertising effectiveness. The entertainment value is in accordance with the ability to fulfil audience needs for "escapism, diversion, aesthetic   Ducoffe, 1996, p.23). Irritation can be defined as the degree to which the advertisement content is disorganised, not polished, and annoying to users (Eighmey and McCord, 1998). Credibility comprises a consumer's confidence in the 'truth' behind the advertising message and its believability (Chowdhury et al., 2006). Peppers and Rogers (1997) define personalisation as the process of acquiring information about the consumer and then deliver a targeted solution directly to the consumer. Finally, interactivity is the level that a consumer can "act on and react to a particular source" (Florenthal and Shoham, 2010, p.30); how engaging the advertisement is.

Informativeness, entertainment, credibility, and irritation
The initial study that analysed the advertising value and how this can affect the attitude towards an advertisement, in general, was that of Ducoffe (1995). A year later, Ducoffe (1996) issued another paper, investigating advertising on the Internet platform. Ducoffe (1995) examined informativeness, entertainment and irritation as the three factors that can ultimately affect the attitude towards advertising. Ducoffe's (1996) study showed that although internet advertising is valuable, respondents found it more informative and less entertaining than its value. In his study, respondents did not consider advertising as irritable while staying neutral on the beneficial aspect of internet advertising. Brackett and Carr (2001) built upon Ducoffe's (1995) study and added credibility with the factors.
Contrary to Ducoffe's (1996) study, their surveyed college students showed that internet advertising is irritating, and insults people's intelligence. Brackett and Carr (2001) confirmed that informativeness, perceived entertainment, irritation and credibility of an advertisement affect the advertising value and consumer's attitude towards advertisement. Nonetheless, credibility added supremacy to Ducoffe's (1995) model and was established as one of the main factors that affect attitude. An and Kim (2007) carried out studies in Asia and North America and found that respondents held negative attitudes towards receiving internet advertisements or perceiving advertisement online, respectively. Two years later, Wang et al. (2009) examined young Chinese people's beliefs and attitudes towards advertising. The information-seeking belief was found to be a strong predictor of the attitude towards online advertisement, while entertainment and credibility were not significant. Wang and Sun (2010) used the same experimentation and compared it with American and Romanian students' beliefs and attitudes towards online advertising. It transpired that information and entertainment were the strongest predictors of the attitude towards online advertisement. When consumers believe that an advertisement is honest and credible, it also enhances the effect on the attitude (Wang and Sun, 2010). Zha et al. (2015) reiterates this, by claiming that credibility is a crucial determinant.
In a study conducted with Portuguese adolescents, Cardoso and Cardoso (2012) confirmed that if the advertising factors are adequately employed, they will result in a more positive attitude towards internet advertising. Saadeghvaziri et al. (2013) confirmed that young Iranian people's attitude is significantly and positively influenced by the information of a product, the entertaining value and social role. Dao et al. (2014) suggested that perceived value can be positively affected by information, entertainment, and credibility in social media advertising. Kim et al. (2016) focused on Facebook advertising and reflected on the relationship between constructs and behaviour towards social media advertising. They claimed that entertainment, information, and Facebook intensity, affect consumers' attitudes and behaviours towards the advertising and the platform, favourably. They agreed on informativeness as being the most important construct that affects consumers. Those advertisements that consumers perceive as irritant are less likely to click on them.
In their comparative study on social media and television advertising, Logan et al. (2012) claimed that Ducoffe's (1995) model does not offer a healthy fit for measuring advertising value. Entertainment, information, and irritation did not predict the attitude towards both TV and social media advertisement among females. Conversely, Saxena and Khanna (2013) argued that advertisement value is enhanced when entertainment and information are provided in an advertisement showing on social media, while irritation reduces it. Aktan et al. (2016) surveyed Turkish students to examine their attitude towards online advertisements. The results showed that information, credibility, and non-irritant online advertisements are high predictors of advertising value and affect their attitude. However, their study revealed that the entertainment factor did not have a directly influence online advertising value.
Lee and Hong's (2016) findings corroborate with Aktan et al.  Ducoffe (1995) Information, entertainment, and irritation affect the advertising value Ducoffe (1996) · More informative · Less entertaining · Not irritable Brackett and Carr (2001) Information, entertainment, credibility, and irritation affect the advertising value An and Kim (2007) · Negative attitudes and perceptions towards advertising · Online advertising less irritable than traditional adverts Wang et al. (2009) · Information is a strong predictor of the attitude towards online advertisements · Entertainment and credibility are not significant Wang and Sun (2010) Information, entertainment, economy, credibility, and value corruption are strong predictors of the attitude towards online advertisements Cardoso and Cardoso (2012) · Entertainment, Information and Trustworthiness showed positive correlations with the attitude towards online advertising · Irritation revealed a negative correlation with the attitude towards online advertising · Female adolescents consider online advertising more informative than male adolescents · Male adolescents consider online advertising less irritating than female adolescents Baek and Morimoto (2012) · Personalisation in advertisements alters its credibility · Perceived personalisation in advertisements makes consumers less resistant to adverts · Personalisation reduces scepticism towards online advertisements · If the perceived advertisement irritation is high, the higher is the avoidance of personalised advertising Logan et al. (2012) · Ducoffe's Advertising Value model does not provide a good fit for assessing advertising value in social media advertising · Entertainment is valued more in social media advertising than traditional advertising · Informativeness is valued less in social media advertising than traditional advertising Ching et al. (2013) The higher the interactivity, vividness, entertainment, and self-referencing in online narrative advertisements, the more favourable attitude consumers have towards a product Saxena and Khanna (2013) · Entertainment and informativeness enhances the advertisement value when present in social media advertising · irritation reduces the advertisement value when present in social media advertising Saadeghvaziri et al. (2013) Information, Entertainment, and Social Role are strong predictors of the attitude towards online advertisements Kim and Han (2014) · Personalisation is a strong predictor of informativeness, entertainment and credibility · Personalisation is negatively associated with Irritation Dao et al. (2014) Informativeness, entertainment and credibility have positive effects on consumers' perceived value of social media advertising Amjad et al. (2015) · Credibility, information, economic system and entertainment are essential predictors of consumers' positive behaviour towards online advertising · Young people have a more significant attitude towards online advertisements Celebi (2015) · Positive information and entertaining value positively affect the students' attitude towards social media advertising · Perceived intrusiveness of social media advertising negatively affect the students' attitudes and behaviours Zha et al. (2015) · Credibility is the key determinant of the attitude towards online advertising · Perceived informativeness and perceived entertainment influence the attitude towards online advertising Murillo (2016) · Perceived informativeness will aid both genders to click more on search advertisements · Entertainment has a strong effect on both gender judgement of advertising value · Irritation has a significant negative effect on perceived advertising value among males but no effect among females · Credibility has a weak impact on the judgement of advertising value Kim et al. (2016) · The likelihood to click on social media advertisements that are perceived as informative is higher than advertisements that are perceived as irritating · Personalisation is thought to be appealing but may be perceived as irritating and intrusive Murillo et al. (2016) · Informativeness has the most substantial effect on advertising value on social media advertisements · Entertainment comes second in the effect on advertising value for social media advertisements · Credibility is the third strongest in the effect on advertising value for advertisements on social media advertisements · Irritation resulted as the weakest predictor of advertising value Aktan et al. (2016) · Credibility is the most significant influence on the creation of advertising value and the attitude towards online advertisement · Informativeness and irritation are the second and third most significant influence on the creation of advertising value and the attitude towards the online advertisement · Non-Irritating advertisements that are credible and informative greatly optimise advertising value Aydin (2016) · Overall, attitudes towards both mobile app advertisements and social media advertisements are unfavourable · Social media users are more irritated by advertisements than mobile app users · Informativeness is the least important factor that affects attitudes towards advertisements · Perceived entertainment and credibility of the advertisements have the strongest effect on attitudes towards advertisements (2016) results regarding informativeness and entertainment. They tested emotional appeal instead of entertainment among South Koreans, which symbolised almost the same traits of this construct. The researchers added creativity as another construct and found that this can be engaging for consumers. Lee and Hong (2016) confirmed that online advertising is useful and valuable, as there is a strong relationship between the advertisement, its value and attitude towards it. Aydin (2016) conducted two surveys to test social media advertisement and mobile advertising in Turkey and found that informativeness appeared to be the least important factor affecting attitude. Ninety per cent of his respondents held unfavourable attitudes towards Facebook advertisements. Compared to mobile advertisements, respondents felt that Facebook advertisements are irritable. His results suggested that perceived entertainment of social media and mobile advertisement are the most influential factors that affect them.
On the other hand, Murillo et al. (2016) found that informativeness and entertainment were the strongest predictors to impact the perception of advertising value amongst Mexican Twitter users. During the same year, Murillo (2016) conducted another study on Mexican millennials, focusing more on mobile search advertisements. Third of his respondents admitted that they would click on a mobile-sponsored search result only if informative. Entertainment had a significant positive impact on the advertising value notion, while a substantial adverse effect with irritation.
Duffett (2020) urges organisations to generate trustworthy, entertaining, and informative YouTube content to elevate advertising and increase awareness among Generation Z consumers. Four years earlier, Dehghani et al. (2016) focused on YouTube and young Italian people. They demonstrated the strong effect that YouTube advertising has on customer purchase intention and that entertainment, customisation (personalisation), and information play a crucial role in enhancing brand awareness and the formation of purchase intent. Irritation is an adverse driver and can affect the drive to purchase intent. Mustafi and Hosain (2020) argued that the association between irritation and purchase intent could be facilitated by advertising value and flow experience. Celebi (2015) found that undergraduate Turkish students hold a positive attitude towards internet advertising and Facebook advertising. It occurs when the advertisement carries positive information with entertaining value. Conversely, the perceived intrusiveness of social media advertising negatively affected their attitudes and behaviours towards social media advertising, particularly Facebook.
One study conducted for different media platforms, spread across six different countries, over two continents and three generational cohorts revealed that different generational segments are attached to their traditional medium (van der Goot et al., 2018). The "net generation", which are the younger generation, are more positively inclined towards advertisements than the other Authors Implications Dehghani et al. (2016) · Perceived entertainment and personalisation (customisation) has the strongest effect on advertising value for advertisements an YouTube · Personalisation (customisation) indirectly influences informativeness, credibility, and entertainment on advertising value · Irritation is an adverse driver and negatively related to advertising value Lee and Hong (2016) Informativeness and advertising creativity are crucial drivers of favourable behavioural responses to a social media advertisement. Islam (2017) · Perceived informativeness, credibility and interactivity are strong predictors of favourable perceptions about the advertising value · No significant relationship between irritation and the attitude towards mobile advertising van der Goot et al. (2018) The Net Generation has a more positive attitude towards advertising in general Ariffin et al. (2018) · Entertainment, interactivity, and irritation are significantly influential on the consumer attitude towards online advertising · Irritation is found to have a significant negative influence on attitude towards online advertising. Irritation may be impacted by credibility and trust Arora and Agarwal (2019) · Personalisation has not been found as a significant predictor of social media advertising value · Credibility is a significant determinant in affecting social media advertising value Daems et al. (2019) Brand interactivity drives the consumer to become more aware of the organisation's selling intent and product-/ brand-related recognition Gaber et al. (2019) · Personalisation is not a vital factor in influencing consumer attitudes towards social media advertisement · Consumers' perception of informativeness, entertainment, credibility and the absence of irritation are crucial and related to their attitudes towards social media advertisements Deraz (2019) · For the Indian participants, informativeness is the main factor when assessing the advertising value of social media advertisements. They feel more comfortable with these advertisements · For the Swedish participants, credibility is the main factor when they assess the advertising value of social media advertisements. They feel more deceived by these advertisements · Most of the social media advertisements are not entertaining to both Indians and Swedish participants · Interactivity is valuable for the Indians but not valuable for the Swedish Duffett (2020) Relevant information and entertainment in social media marketing resulted in favourable attitudes towards advertisement and higher purchase intentions Mustafi and Hosain (2020) · Informativeness, entertainment, credibility, and incentives have positive and significant effects on consumers' purchase intention · The relationship between the irritation levels and purchase intention can be mediated by flow experience and advertising value generational cohorts (van der Goot et al., 2018, p.289). As the net generation grew in an online world immersed in advertisements, the researchers suggested that advertisements for young people are an ordinary matter and not unfriendly. Hence, young people had a positive attitude towards advertisement, irrespective of the medium. Amjad et al. (2015) determined both credibility, information and entertainment are the critical predictors of positive behaviour towards online advertising.

Personalisation
Baek and Morimoto (2012) was the first group of researchers in our list that introduced personalisation as another factor. Twopronged perspectives dominated the field of study when it comes to personalisation. This factor was found to be positive and could alter an advertisement's credibility (Baek and Morimoto, 2012). They carried out a study focused on targeted, personalised advertisements of business e-mails, and direct mail, and their results suggest that scepticism towards advertisement is lower if a personalised advertisement is sent to a specific customer. Kim and Han (2014) and Dehghani et al. (2016) proved that personalisation was a strong predictor of informativeness, a significant precursor of entertainment and credibility, and negatively associated with irritation. Kim and Han (2014) were the first researchers to analyse five constructs from the six principal factors.
Not all studies found personalisation as crucial. Kim et al. (2016) argued that although personalisation might seem appealing, this could be regarded as irritative and intrusive. Hence, the researchers connected both personalisation and irritation, as one is a precursor to the other. Gaber et al. (2019) confirmed that personalisation was not an essential factor in influencing Egyptian Instagram users' attitudes. However, the consumers' perception of informativeness, entertainment, credibility and the absence of irritation were crucial and related to their attitudes towards advertisements. Even Arora and Agarwal (2019) concluded that personalisation was not a significant predictor of the social media advertising value. However, the researchers found that credibility is a determinant in affecting the advertising value. Ching et al. (2013) added another factor -interactivity, and tested it on the Taiwanese online platform, using an online questionnaire. They confirmed that a higher level of interactivity in online narrative advertisements led to more positive attitudes. Islam (2017) Ariffin et al. (2018) suggested that entertainment, interactivity, and irritation are significantly influential on consumer attitude. Irritation was found to be impacted by credibility and trust.

Interactivity
Interactivity can differ from one culture to another. This was strongly felt in the study done by Deraz (2019), where two focus groups were conducted in Asia and Europe, respectively. It was found that interactivity in an advertisement is valuable for Indian customers but not valuable to Swedish. In this case, even informativeness and credibility differed, where Indians feel more comfortable with informativeness in advertising, while the Swedish feel deceived by advertising.

Young People and Gender
Advertising can have a pervasive influence on young people, with some adverse effects impacting them (Kuppuswamy and Narayan, 2010). Nonetheless, it was noted that exclusive research that focused on the influencing factors affecting young people's attitude towards online advertising were few. This notion was evident in the selected studies and even among all the other articles that were part of the screening phase. No study focused only on the whole age range of young people, from 10 to 24 years. Still, different papers focused on ranges within the young people bracket (e.g. Dao et al., 2014). Nevertheless, only six studies included young people under the age of 16. It was observed that ages between 10 and 15 are the least investigated. For example, Daems et al. (2019) researched the targeted advertising in an online environment, specifically on young teenagers between 11 and 14 years, with a particular focus on the effects of advertising integration and interactivity and how they affect their memories.
Ducoffe (1995) did not specify the age in the study, although three studies stated that the research was conducted with college students (Brackett and Carr, 2001;Saxena and Khanna, 2013;Wang and Sun, 2010). Ducoffe's (1996) study involved participants with an average age (Mage =32). This study was included as it was part of the pioneering work by Ducoffe. Other studies covered a part of the age group in their study, either as part of a cultural comparison study (e.g. Islam, 2017) or to focus on different generations (e.g. van der Goot, 2018).
The gender was balanced across almost all studies. Overall, female respondents account for 53 per cent. In Logan et al. (2012), only the females' advertising value perceptions were examined; No males were involved in the study. On the other hand, there were studies that female users were in the absolute minority -mostly from India (e.g. Saxena and Khanna, 2013) and Pakistan (Amjad et al., 2015).
Other studies focused more on gender differences but included only adolescents as part of their extensive study. Dao et al. (2014) argue that gender difference in young people had an immaterial effect, although the findings suggest that a significant positive effect of user experience exists on online purchase intent. Cardoso and Cardoso (2012) claimed that although there was a consensus between males and females on entertainment and credibility, females regarded online advertising as more informative and irritating. Murillo (2016) partially corroborated with Cardoso and Cardoso (2012) study, as he argued that both genders are strongly affected by entertainment on the valuation of advertising value. However, the irritation does not affect females and impact the perceived advertising value negatively among male respondents. Murillo et al. (2016) claimed that credibility in advertising demonstrated effects on gender, as it was more important for female millennials than males. Saadeghvaziri et al. (2013) found that males are more positive than females in their attitude towards online advertising, but no variances in their behaviour.

CONCLUSION
This systematic literature review has brought forward a collection of papers about the factors that influence the attitude towards online advertising. This study reviews earlier studies in this area through a systematic approach and evaluation of the emerging two main research themes. This research aims to identify and examine the significant factors influencing young people's attitudes towards online advertisements and how these factors influence their attitudes.
From this study, it was concluded that six influential factors affect the attitude towards advertising. Almost all the chosen academic studies found a relationship between more than one factor and the attitude towards advertising. The studies have predominantly placed information, entertainment, and credibility as the most significant predictors of the attitude towards online advertisements for young people. Irritation was placed as the factor that has a significant negative influence on attitude towards online advertising. Hence, the studies showed that the more the three positive factors are present, the more favourable the attitude towards advertising is, while the more irritative the advertisement is, the more present the negative attitude is.
On the other hand, there are mixed perspectives when it comes to personalisation. Some studies found that personalisation reduces scepticism towards online advertisements (e.g. Baek and Marimoto, 2012). Adversely, other studies claim that it deters consumers, as it may be perceived as intrusive (e.g. Kim et al., 2016). The most recent studies show that the online audience is generating a more obscure perception towards personalisation. This may be the result of heightened privacy concerns and widespread knowledge about advertising. Interactivity is found to be positive and can foster connectedness between young people and online advertisement.
Only one study showed that interactivity might not be perceived as valuable by some participants (Deraz, 2019).
There was no academic paper that linked all the factors altogether in one study, but few incorporated five factors out of six (e.g. Islam, 2017;Gaber et al., 2019). Nine studies had the four constructs depicted by Brackett and Carr (2001), focusing on informativeness, entertainment, irritation, and credibility.
All the studies included young people, but not necessarily targeting only them. No study included the full age range of young people solely. Even more, the younger cohort of young people was the least studied. This may be due to ethical concerns and parental consent, apart from the problem of access. It revealed a lacuna in the studies regarding the understanding of the young people's attitude towards advertising.

Limitations
Although much care was given to the range and criteria of the corpus, this literature review still has some limitations. First, as with all systematic literature reviews, the study was based on the search strings employed and the databases that were chosen. Nonetheless, the chosen studies provided a robust understanding of the factors that affect young people's attitude towards online advertising. Second, this study excluded grey literature and speculative papers as it was imperative to base all the study on solid grounds, devoid of any assumptions or opinions. Furthermore, we restricted our choice to publications written in peer-reviewed journals rather than reviewing documentation in conference papers or chapters in edited books.

Future Research
A significant gap in the current knowledge is that few papers are explicitly focused on the entire age range of young people and their attitudes towards online advertising. Even fewer studies are focused on the younger bracket of young people, ages between 10 and 15 years. Future research needs to be conducted strictly on young people, even more, when one considers that around 92 per cent of young people in EU countries use the Internet daily on their mobile phones (Eurostat, 2020).
Another critical lacuna in the knowledge that emerged in this review is the dearth of academic literature on retargeted advertisements. As Zarouali et al. (2016) admitted in their study, research about retargeting is scarce and urged academics to focus more on this phenomenon that has spread rapidly in the online environment, with researchers not keeping abreast with this reality. Retargeting continues to evolve commercially, but remains relatively unexplored (Bleier and Eisenbeiss, 2015). Future researchers need to consider applying these six constructs in a retargeting environment to understand better and explain the relationships and influence that this may have. Even more, qualitative research will also aid in contributing to a better understanding of the dynamics of retargeted advertisements and how these factors influence young people's attitude towards them.