Design for Persuasion — Generate ideas using Contrast Principle

We live in an extraordinary complex, a busy world with a rapidly changing environment(Yes…So busy…could not sleep more than 10 hours in a day). Our limited knowledge, shorter times, limited experience, uncertainty environment have added to life’s complexity(Yesterday’s food in that restaurant was horrible….I will not tell you the name of the restaurant). To deal with it, we need shortcuts. We as humans, use heuristics, which are simple, efficient rules to form judgements and make decisions.

These mental shortcuts usually involve focusing on one aspect of a complex problem and ignoring others.These rules work well under most circumstances, but they can lead to systematic deviations from logic, probability or rational choice theory — Wikipedia

These heuristics or Persuasion Principles are as follows- Contrast, Reciprocity, Authority, Liking, Commitment & Consistency, Social Proof and Scarcity. Out of these mental shortcuts, we will now focus on “The Contrast Principle”. I’m providing some references from Dr.Robert Cialdini’s writings

The Contrast principle affects the way we see the difference between two things that are presented one after the other.

  • If we lift a light object, and then a heavy object, we judge that second object to be heavier than if we had lifted without first trying the light one. (oh…carrying those shopping bags from supermarket — Have not yet figured out the ideal weight for each hand)
  • When we are talking to a beautiful woman, then joined by an unattractive one, the second women will appear less attractive than she actually is. (Let’s not show it to wife…..if you say anyone beautiful, whatever the principle is……..better be safe)
  • Research shows that many feel their lovers are less attractive than she is, as popular media has bombarded them with unrealistic attractive models. (Now I know who is responsible for Break-ups. Don’t they understand the pain of people(men?) Let’s ban the magazines.)
  • After placing one hand in cold water, another in hot water, if we keep both hands in warm water in the same bucket, the hand that has been in cold water feels as if it is in hot water, and other hand feels as if it is now in the cold water. (mmmm….Hope fingers were not burnt)
  • Clothing stores instruct sales personnel to sell the costly item first. After seeing an expensive item, in the beginning, the prices of other items will not seem as high in comparison. (Yesterday, a friend went to buy a suit for 10k. Finally bought one for 17k. And accessories. Right. Friends are supposed to more than us….)
  • Real estate brokers would start with a couple of undesirable houses, which were not intended to be sold, but to be shown to prospective buyers, so that their genuine houses would benefit from the comparison. (Oh! Now I’ve started to hate my staying place. Sometimes, truth doesn’t let us live.)

Though this contrast principle is widely used in marketing(I understand Why Seth Godin wrote a book on the title “All Marketers are Liers”), designers too have been using sub-consciously(Hey, but we don’t cheat…..Mother Promise….You can trust….No. I’m not trying to harness Authority Shortcut…). Better Usability is nothing but a “Contrast Principle” where User sees a difference from a product’s earlier version or against other products. If there was no prior product, then customer compares against doing that particular in an earlier circumstance. iPod killed MPman, Walkman and other Mp3 players — Better Usability, Functionality, Aesthetics — Contrast Principle. (Vow! White Earphones, Scroll Wheel…..Nah…..They are ok…not great. iTunes Store, Interface and Songs @ 99cents man….Killer.)

Let’s see whether we can use this principle to generate ideas for a product. This idea came to my mind while bathing today. Bathing soap was in my mind that time. So, Let’s apply the principle on bathing soap.

Note: Focussed research is needed to validate any ideas. Since we do not have any research data, we are going to just generate ideas and not validate anything.


You buy a soap — You can use it for 20 days….Great…..But as the soap size diminishing every day, how do you feel after a week? After 12 days? In the first week of use, we can hold and use the product comfortably, and gradually, it becomes tedious, and then intolerable to use.

The soap keeps shrinking every day. By Contrast, can you maintain the size? How about soap outer surface being made of a hollow porous silicon membrane, and the gap filled with soap liquid. Soap oozes out when the silicon outer body is slightly squeezed. You can refill it when the soap liquid is completely drained off.


Most of the soaps have a smooth surface. Can we make it rough? Bumpy, Hard, Rugged, Rocky, Jagged, Stony, Unleveled?


Why should soaps have only one fragrance throughout the use? As the soap dissolves, can the fragrance keeps changing. Colours too can be varied.

The soap is built as layers — each layer can have different colour and representative fragrance. As the outer layer of soap dissolves, the next colour will be visible and soap’s fragrance too changes. Make the users feel fresh about the product every 4–5 days. Make them wait for the mystery colour and fragrance. Sustain the user’s interest.


Solid or liquid medium for the soap? Apply Contrast — Air -Spray. Let’s spray the soap. But advantages? Uses? Spray — Spray — Less soap over a larger area, Man. Massive savings. A quicker way to spread the soap over the wet body. Wonderful usability. Tired of soap falling down? Don’t worry. Soap will not dissolve faster as bathing water is not going to fall over the soap.


Soap — what temperature — they are at room temperature — Yes, there are some cool soaps like Dettol Cool. But for cleaning, don’t we need warm soap or hot soap? Yes, after dining, we wash our hands in warm lime water.

How about a soap that heats up when water falls? Can we design a device, where soap can be heated to required temperature before use? This device may have other applications too. Or the device can prevent soap contamination.


During continuous use, we always struggle with the hindmost portion of soap. Generally, 30% of soap is difficult to use and when it reaches the size shown in below figure, it is discarded.

Instead of completely soluble, why can’t we design with part of the soap being Non-Soluble.

The core — central area can be of any Non-Soluble material. Can the customer give the core back to retailer and get some discount over the next soap purchase? You get loyal customer? The core can be of interesting design or a useful object for a user. Example — It can be a toy for a kid. Don’t tell me that kids will try to use the soap faster in order to see the toy and use it. (That’s a good news for manufacturers — Will you tip me for the idea)


We have soaps of all sizes. S, M, L, XL, XXL….ah! soaps for travelling….they are of smaller in size. What can we do in this? Can the Soap be of the size of a small c……candy? Being tiny — Advantages — I’m tired of all those Soap Papers.

  • Take the wallet from the trouser
  • Open the wallet
  • Remove the Soap paper pack — where to keep the wallet? We are people from circus man.
  • Tear the strip using both the hands(I don’t know where you are going to keep the wallet while you are tearing the strip) — Not easy one with one hand
  • Close the pack and keep it in the wallet (without opening the wallet — we are magicians)
  • Don’t forget to keep the wallet back inside the trouser — or you will regret that paper soap made you lose the wallet. Don’t curse anyone making a product dependent of another accessory
  • Finally, washing the hands. Thank God.
  • Now, where to throw this used soap paper? Forget it. Let’s put it in our shirt pocket. (Yes, you can find dustbin near sometimes — Should I write the procedure to use again — Forget it)

Why can’t the soap be a small, soft candy like 50p chocolate — I take it and wash — it just dissolves and go…No disposal needed.

Maybe a smaller one, with 3–4 flat pieces. Flip it with one finger, take it and use.


Can the soap be sharp or having pointed projections — Can the soap be similar to products used in sensory therapy? The balls in sensory therapy provide relaxation for fingers. When the balls are rubbed over the body, it relaxes muscles and provides sensory stimulation. Can the soap serve both functions? The projections can be designed with variable heights so that the soap’s use can be stretched to cover more days.

I’m good at catching. Let me join a Cricket Team.


Instead of Soap medium being Solid or Liquid — Why cannot be of paste? Advantages — I can take paste and apply over the dry body. Once everywhere it is rubbed — I can spray a little amount of water to wet the body. Soap foams. You can save water, consume less soap, save time. (I promise you that I’ll not brush my teeth with this bathing paste. Are you going to supply me a soft brush for bathing……Great. )

Should I conclude now…… Yes. Just focus on One main Product Feature, Make it as contrast as possible. Please don’t compare against a competitor product’s features — Erase your competition or competitor product from your mind — Focus, only on the user and user’s jobs to be done.



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