Marketing Psychology: Key concepts and the application of psychological effects in advertising

1. Psychology of Relevance (Relevance)

In psychology, according to the principle of Selective Attention, people tend to only pay attention to information they find valuable or personally relevant. This concept is highly significant in marketing psychology and behavioural marketing. When an advertisement appears and directly reflects the customer’s needs or interests, they are more likely to stop, engage, and evaluate it more carefully. According to Environics Research, 79% of consumers tend to buy from brands that share similar personal values. This demonstrates that relevance between a brand and a consumer’s personal value system is a crucial driver in customer decision psychology. Furthermore, YouGov’s Seasonal Holidays Study revealed that up to 96% of consumers make purchase decisions based on personalized ads that match their needs and preferences. Therefore, relevance in advertising—under selective attention triggered by personal needs—does not only stimulate interest but also increases the likelihood of positive behavioural response. When ads deliver relevant and valuable information, they can effectively trigger purchase intent and drive higher conversion rates for both brands and consumers.

Application: To apply the principle of “relevance” in practice, marketers should leverage user behavioural data to personalize ads based on customer segmentation, interests, location, or shopping journey. For example, a skincare product ad will perform better when shown to users who have previously searched for terms like “sensitive skin” or “adult acne treatment”. This strategic use of behavioural segmentation increases engagement and improves ad performance.

Confirmation Bias clearly manifests in consumer behaviour in Vietnam when evaluating and trusting advertising formats. According to a Nielsen report, 81% of Vietnamese consumers stated that they trust ads recommended by friends and family. This indicates that when a brand is introduced by someone familiar, consumers are inclined to trust it without seeking further verification. Additionally, 64% of consumers said they trust online user reviews. These figures show that people tend to seek information that aligns with their existing beliefs and personal experiences, reinforcing their cognitive bias. In the landscape of digital advertising, where marketing psychology plays a crucial role, understanding confirmation bias helps brands craft more persuasive communication strategies that align with expected beliefs and social proof dynamics.

Application:  To leverage confirmation bias, brands should actively use real customer testimonials, social proof, KOL endorsements, or referrals from communities close to the target customer segment. Furthermore, advertising content should reflect opinions, values, or experiences that customers already believe in, thereby enhancing persuasion and conversion potential.

3. FOMO – Fear of Missing Out in Customer Behaviour

FOMO (Fear of Missing Out) is a powerful psychological trigger that makes consumers feel anxious about potentially missing out on exciting experiences that others are enjoying. This emotional response is often exploited in behavioural marketing strategies to drive immediate action through scarcity tactics and time-limited offers. According to research from Eventbrite, 69% of Millennials experience FOMO daily, highlighting their sensitivity to marketing messages that tap into this psychological effect. FOMO is a strong motivator in customer decision psychology that can accelerate buying behaviour when used effectively.

>>> How to Incorporate FOMO into Ad Headline? Clickbait tricks to optimize your campaign 2025

Application: By using messages like “Exclusive offer for the first 100 customers” or “Only 24 hours left to claim this deal”, brands not only capture attention but also create urgency that encourages immediate action. When executed correctly, leveraging FOMO psychology not only increases ad engagement but also drives stronger purchase intent and accelerates conversion rates, helping businesses optimize their marketing strategy and customer journey.

The Halo Effect is a psychological phenomenon where consumers perceive all products from a brand as high quality simply because they have a positive impression of one flagship product or the brand image itself. This demonstrates that a strong brand identity can shape trust and influence consumer decision-making. According to research from Econsultancy, 32.2% of consumers said that a website’s professional design impacts their trust. Furthermore, 48% feel safer shopping on websites with verified credibility signals. The Halo Effect, when applied strategically, can enhance overall customer perception and shorten the evaluation time during the buying decision process. In digital marketing psychology, this effect reinforces the importance of consistent branding across all customer touchpoints.

Application: To harness the Halo Effect, businesses should invest in building a consistent, professional, and trustworthy brand identity across all digital platforms—from website design and product packaging to the overall customer experience. Launching new products under an already trusted brand umbrella increases credibility and accelerates customer acceptance in the purchase journey.

The four psychological triggers above—Relevance, Confirmation Bias, FOMO, and Halo Effect—play a significant role in influencing consumer behaviour and customer decision psychology. Understanding these behavioural marketing insights allows brands to personalize communication based on customer segmentation, improve ad effectiveness, and build stronger long-term customer relationships. By aligning messaging with user motivation and perception, marketers can optimize campaign performance and create impactful digital advertising strategies.

About SmartAds, formerly known as eClick, developed by FPT Online – one of the leading pioneers in digital technology and media in Vietnam. Through continuous innovation and development, with an extensive network of premium publishers, SmartAds affirms its pioneering position in applying brandformance solutions in the Vietnamese market, aspiring to become a trusted partner accompanying brands in their online customer acquisition journey. If you're looking for an advertising solution that optimizes both awareness and performance, don’t hesitate to create an account and experience campaign setup on SmartAds here.