Color Combos

This visual companionship feels like social companionship.

Lonely person prefers similar shades of purple

Lonely-Similar-Colors-min

Lonely People Prefer Similar Colors

Lonely people prefer similar colors because this visual companionship feels like social companionship.

Conservatives buy a greater variety of products than liberals, but this pattern reverses during crises (e.g., COVD-19).

Politics and Variety

Male chatbots improve satisfaction when they apologize, while female chatbots improve satisfaction when they show appreciation.

Chatbot Gender and Angry Customers

A 10% increase in hours of safety training reduced hazards by 6%-10%.

Safety Trainings Are Effective

Round Products

Tall and skinny products seem rational, while round products seem friendly and emotionally gratifying.

Skinny bottle is rational; round bottle is friendly

Chubby-Products

Round Products Seem Friendly

You feel more kinship with somebody who bought a similar item, especially when it was experiential (vs. material).

Bonding Over Experiences

Participants were less apt to trust strangers in a game if they had used their phone beforehand.

Smartphone Use Reduces Trust

We feel less empathy due to AI's lack of emotions, which can numb the anticipated guilt from questionable decisions. You can reduce this numbness by injecting AI tools with humanlike traits.

AI Interactions Trigger Immoral Behavior

Vertical Angles

Upward angles look effective, luxurious, and authoritative. Downward angles look easy, portable, and sustainable.

Two angles of coffee packaging. Upward angle looks luxurious, effective, and authoritative. Downward angle looks easy, portable, and sustainable

Choose an Upward or Downward Angle for Product Images

Choose the Best Vertical Angle for Product Images

What's the optimal angle for a product image? Why does it matter?

Researchers found that judges are more likely to cite previous cases as precedent if there's a Wikipedia article written about the case. And those judgements share similar wording from the articles.

Wikipedia Influences Legal Verdicts

Movies perform worse in foreign markets when lead actors look similar to each other. Foreign audiences struggle to distinguish and remember them.

Cross-Race Effect in Movies

Gratitude fuels a sense of meaning in life, which suppresses boredom. 

Grateful People Are Less Bored

Numbers and Attention

A listing of flights with a circle around a listing price of $2111

Repeat Digits For Prices in External Marketplaces

Show Repeated Digits in External Marketplaces

A new study shows that you can grab more attention in online marketplaces by choosing the right digits in your price.

A new paper describes a way to deliver optimal ads in real-time by studying the facial expressions of viewers. Sounds creepy.

Smart Ads

People Dislike Angular Furniture

Research shows that people prefer straight lines (vs. tilted lines). A new study found that music albums with straight lines perform better across metrics (e.g., chart rankings, expert ratings, listening time).

Album Design

Round Numbers

Round numbers feel larger. For example, a drink seemed more energizing with 100mg (vs. 102mg) of caffeine. Therefore, a round discount (25% off) often feels bigger. However, precise numbers feel unstable. You imagine 24.7 on narrow scale in which any movement — even a slight nudge — will change this number. Therefore, customers feel motivated to grab a precise discount (e.g., 24.7% off) because it feels like it can change (e.g., disappear) at any moment.


Round discounts seem big, while precise discounts seem urgent.

Show a Round or Precise Discount-min

Choose a Round or Precise Discount

Which discount is better: 25% off or 24.7% off. I used to think 25% would perform better, but a new study sheds light. 

Playing video games after work rejuvenates you because of the psychological detachment.

Video Game Psychology

It feels less harmful on the environment.

Customers Feel Less Guilty Wasting Organic Food

After bad service, businesses seem more sincere when they attribute their mistake to incompetence (e.g., lack of skills). It makes the apology seem costlier, thus more sincere.

Apologies and Incompetence

Magical Number 4

Humans feel choice overload when they see too many options. But how many options are too many? Try showing 4 options or fewer because of an ability called parallel individuation. If you see 4 items, your brain knows that 4 items exist immediately upon seeing them. You don't need to count them. But this ability collapses with 5+ options. Assortments with 5+ options will feel like a lot. Group these options into smaller sections in order to minimize feelings of being overwhelmed.

Four items are a critical threshold because of parallel individuation.

Show 4 Options or Fewer in Choices-min

Show 4 Options or Fewer in Choices

Four items are a critical threshold in choice overload because of an ability called parallel individuation.

Based on lab studies and real-world data, you're more likely to complete an online checkout when the weather is nice.

Sunny Weather Lowers Cart Abandonment

Customers give larger tips when they see an emoji in the vicinity because it actives a positive emotion.

Emojis Increase Tipping

Faces seem larger upside down, but letters and words seem smaller.

Upside-Down Illusion

Why Number 4

Digit Averages

You should typically reduce the left digit in prices. $5.99 feels lower than $6.00 because your eyes are anchored to the left digit. But $5.99 has a couple 9’s, which are high digits. Is that bad? Usually this effect is trivial because the left digit is more persuasive. Though it's important for prices in the thousands because customers focus on these left digits. Therefore, reduce digit averages for these prices. $2111 is more persuasive than $1999 because the average is lower (1.5 vs. 7.0).


The left-digit effect backfires for high prices (e.g., $1999) because customers focus on the later digits.

Reduce Digit Averages When Pricing in the Thousands

Reduce Digit Averages For Prices in the Thousands

Certain digits can make a price feel lower. Instead of reducing the left digit, sometimes it's more effective to reduce the digit average.

People boost their status by trying to be wealthy or cool. But these two ideas are inversely related: Try to be wealthy? Admirable. Effortlessly wealthy? Pathetic. Try to be cool? Pathetic. Effortlessly cool? Admirable. 

Trying to Be Cool

Customers believe that smaller packaging is more unfair than increasing the price. You can curb these negative emotions by transparently communicating the smaller size, while showing internal costs to justify this change.

Product Downsizing Seems Less Fair

Listing your home on AirBnb? Show a cute pet in your photos. You'll seem friendlier and increase bookings.

Cute Pets Increase Home Rentals

Friendly vs. Competent

Most salespeople believe that competence is more important than friendliness, but both are equally important at different times. Customers prefer calls that follow this sequence: friendly-competent-friendly. Even though a competent greeting (e.g., How may I help you?) is more efficient, customers prefer a friendly greeting (e.g., I hope you're enjoying this fine day?).

Customers are happier with support calls when they unfold in this sequence: friendly-competent-friendly.

"Hi, great day" is a better greeting than "Hi, how may I help you?"

Start and End Conversations With Warm Language-min

Start and End Conversations in a Friendly Tone

Which trait is more persuasive in a salesperson: friendly or competent. Researchers measured each trait.

Customers feel more curious, which intensifies their desire to buy.

Waiting in Line is Persuasive

Researchers have argued that people are economically and psychologically motivated to delay costs. But not everyone. Some customers want to pay more money sooner (vs. less money later). Why? They want closure. Otherwise tasks would linger on their minds. 

Some Customers Can't Wait to Pay

When customers see (and resist) a competitor promotion, they become more loyal to their current brand, spending more money with them.

Competitor Promotions Increase Loyalty

Eye Fixations

Customers prefer bundles in which the best product is toward the left. If you read from left to right, you start evaluating the leftmost item first. Hmm, not appealing? You feel lackluster emotions, which discourages you from evaluating the subsequent items.

If you read from left to right, you evaluate other stimuli in this pattern.

Keep Focal Products in the Left Side of Bundles-min

Place a Focal Product in the Left Side of Bundles

If you read from left to right, you evaluate other stimuli in this pattern, including product bundles.

I updated my tactic on currency symbols. It suggested removing currency symbols when possible. And sure, it might work in upscale restaurants (which was the context of the original study). But in most scenarios, customers need currency symbols to know whether numbers are, in fact, prices. So keep them, but modify them slightly. See the update for details.

I updated my tactic on currency symbols. It had suggested removing currency symbols when possible. And sure, it might work in upscale restaurants (which was the context of the original study). But in most scenarios, you need currency symbols. However, you should modify them slightly. See the update for details.

Currency Symbols

When you drink tea or coffee, you can detect relationships in products faster. If there's a similar (yet worse) product, the superior option seems even better.

Caffeine Increases the Decoy Effect

We know that decoys influence people to choose the superior option, but these nudges also reduce the amount that people consume this chosen item.

Decoy Effects Reduce Consumption

Animate Prices With Light Physics

Animation speed influences perceived size. The faster an object moves? The smaller it seems. It might happen with prices too. If you ease scrolling on a pricing page, the prices would move up faster and easier, as if the prices were small and light.

Speed and movement can influence perceived size. Perhaps animations or scrolling behavior can influence the size of prices.

Price moving as if it were small and light

Animate Prices With Light Physics-Final-min

Speed and movement can influence perceived size. Perhaps animations or scrolling can influence the size of prices.

Anchoring is a robust effect. Think of a high number? You perceive a new number (e.g., price) to be lower. But these effects were eliminated when participants walked into a new room (vs. walked down the same hallway; Ongchoco, Walter-Terrill, & Scholl, 2023). New scenery can reset our mindset. The same effect might happen if you bring users to a new layout screen in your app or web funnel.

When Persuasion Expires

What if you recommend a product to your friend, but they don't like it? Turns out, you start feeling less enjoyment with the product, questioning your original desire for it (Hall, Hyodo, & Kristofferson, 2023).

Questionable Recommendations

Faces generated with AI look more average, so they feel more trustworthy than real faces (Nightingale & Farid, 2022).

AI Faces Are More Trustworthy

Price Divisibility

Customers preferred a 4-pack of body wash for $16 (vs. $15.30). If customers see a 4-pack for $16, they calculate $4 per item. This calculation shifts their attention from the bundle to the items, which helps them imagine usage scenarios (e.g., one for me, one for my son, one for downstairs).

Customers prefer prices that are divisible by the purchase quantity because it helps them imagine using these products.

Set Bulk Prices With a Divisible Quantity-min

Set Prices That Are Divisible By Purchase Quantities

Sometimes I see specific prices for durations, such as $63.46/hour or $13.45/month. But are they effective? This week's study might shed light. See my LinkedIn post which expands on this idea.

Use Duration Prices That Are Easy to Multiply

Time Windows

"Jan 1 - Jan 6" feels shorter than "Mon - Sat" because the time window is shorter in a monthly scale.

Monday to Saturday is large portion of a weekly scale, but Jan 1 to Jan 6 is small portion of a monthly scale

Time Intervals Seem Shorter in Calendar Dates

Time Intervals Feel Shorter in Calendar Dates

New research shows that time windows seem shorter in a calendar framing (Jan 1 to Jan 6) compared to a days-of-the-week framing (Mon to Sat).

You repurchase the same brand if this new purchase resembles the previous purchase (e.g., same retailer, same weekday, same basket size; Koll & Plank, 2022).

Same Cues, Same Purchases

Even 15 years later. But the effect was less relevant for tech jobs (Malik, Singh, & Srinivasan, 2023).

Attractive MBA Grads Secure Better Jobs

They rely on God, not people. This effect happened in various contexts (e.g., applying for government aid, asking for favors, requesting donations from crowdfunding; Liu, 2023).

Religious People Are Less Likely to Seek Help

Rationalizing Behavior

Otherwise customers might infer that products are unappealing. 

End of a product catalog with "Can't Decide?" and relevant links (e.g., Take Our Quiz, Talk to an Expert)

Justify Why Customers Reached the End of a Catalog

If customers reach the end of a catalog, they contemplate the reason. One hypothesis? They didn't like the products. Therefore, shift this rationale.

Whether it's a gas-guzzling car or raunchy movie. Renting feels less guilty than buying because we're not owning the questionable product, which would tarnish our self-identity (Kang, & Park, 2023).

We Prefer Renting Unethical Products

Men are worried that other people would perceive them negatively, whereas women share negative gossip to gain comfort (Carbone, Loewenstein Scopelliti, & Vosgerau, 2024).

Men Are Less Likely to Share Negative Gossip

Customers choose the same option or flavor if they pay with cash. Why? Because cash payments are painful. Customers feel more pressure to justify their purchase, so they choose options that are easier to rationalize (e.g., their favorite; Huang, Siddiqui, & Ghosh, 2023)

Cash Payments Reduce Variety

Present Tense

These actions feel like they're still happening.

Home inspection summary: porch is stable, faucet looks good, I don't see termites

List Completed Actions in the Present Tense

List Completed Services in the Present Tense

A recent study confirmed that language is more persuasive when framed in the present tense.

Researchers tested payment vibrations (e.g., none, low, high) in a mobile app. Ironically, low vibrations were most painful. Customers felt like they were losing more money (Manshad & Brannon, 2021).

Low Vibrations Increase the Pain of Paying

Researchers replicated the QWERTY effect: Right-handed people prefer words that contain letters from the right side of a keyboard (e.g., jump, milky, nylon). Something about them feels right. Pun intended.

The QWERTY Effect

Customers behave properly in front of humans. But in front of AI? They lie, cheat, and steal. People are more likely to cheat on their taxes if they use software (vs. human advisor; LaMothe & Bobek, 2020).

AI Leads to Unethical Behaviors

Writing this email

Padding and Price Effect

In physical stores, the amount of space influences prices. A lot of empty space? Managers need to raise prices to pay for this real estate. This belief is so familiar that, ironically, customers apply this logic with online stores. In a digital catalog, products seem more expensive when surrounded by more padding, even though this space doesn't cost anything. Restrict padding in your catalog if customers want a good price, but add padding if customers want high quality.


More space activates our experience with physical stores, where real estate is expensive.

Two assortments of products. The spacious assortment looks expensive

Products Seem More Expensive With Padding

Products Seem Expensive With More Padding

In a digital catalog, the amount of padding can influence the perception of prices, based on our experience with physical stores.

I added new research to my tactic on prices and font sizes. It offers more guidance on how to use this technique.

Prices and Font Sizes

In a study with 30,000 banking customers, people spend more if they get paid more frequently. Regardless of the amount. If you get paid more frequently, you believe that you possess more funds to pay for goods and services (De La Rosa & Tully, 2022).

Frequent Paychecks Increase Spending

They prefer sharp fonts, logos, products, app icons, and other design elements (Chen, Jiao, Fan, & Li, 2021).

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