Serial Position Effect
Users have a propensity to best remember the first and last items in a series.
Read the original on lawsofux.com →
The scenario: Snackly, a food-delivery app. Two series matter here: the five slots of the bottom navigation bar, and the nine cards of a “Popular dishes” carousel. First and last positions are the two memory anchors of any series — primacy and recency — yet the “before” spends both anchors on low-value items and buries the money actions in the middle.
Caesar side salad
Garlic bread
Penne arrabbiata
Margherita
Truffle burrata pizza
Minestrone
Caprese
Tiramisu
Homemade lemonade
Golden Wok
Chinese · 4.6 ★ · 20–30 min
Taquería Sol
Mexican · 4.4 ★ · 15–25 min
Patty Shack
Burgers · 4.7 ★ · 10–20 min
Kaiyo Sushi
Japanese · 4.8 ★ · 25–35 min
Pita Corner
Greek · 4.5 ★ · 15–25 min
Bombay Express
Indian · 4.6 ★ · 20–30 min
Truffle burrata pizza
Margherita
Penne arrabbiata
Caprese
Minestrone
Caesar side salad
Garlic bread
Tiramisu
Order again: your usual
Golden Wok
Chinese · 4.6 ★ · 20–30 min
Taquería Sol
Mexican · 4.4 ★ · 15–25 min
Patty Shack
Burgers · 4.7 ★ · 10–20 min
Kaiyo Sushi
Japanese · 4.8 ★ · 25–35 min
Pita Corner
Greek · 4.5 ★ · 15–25 min
Bombay Express
Indian · 4.6 ★ · 20–30 min
🔍 What changed
- Primacy: the first item in a series gets rehearsed most and remembered best — so Home now opens the nav bar and the signature dish opens the carousel.
- Recency: the last item is freshest in memory when it's time to act — so Cart closes the nav bar and the “Order again” shortcut closes the carousel.
- The middle positions, where recall is weakest, now hold the browse-y, lower-stakes items (Search, Promos, Orders).
- Edge slots also help ergonomics: thumbs find the first and last tab without looking.
- No tab or dish was added or removed — only the order changed.
💼 Explaining it to stakeholders
“People reliably remember the first and last items in any row — the middle blurs. Right now our two revenue-critical destinations, Home and Cart, sit in that blur while Promos and Help occupy the prime seats. Reordering five tabs costs nothing to build, and it puts the actions that end in a purchase in the two positions users find by muscle memory.”