My colleague recently had a disagreement with a client about the colour of two items. The client claimed both items were the same colour, while to my colleague one was red and one was green. I can confirm that the two items were indeed red and green. My colleague and I know another colleague, who is red-green colourblind, who cannot tell the difference between these two items either. My colleague strongly suspected our client is red-green colourblind and not aware of it. The situation was very awkward. It turned out the client was colourblind, but until the incident with these two items, not aware of his colourblindness. As you can probably imagine, this did not go down smoothly. The client got frustrated because he was thinking my colleague was joking with him. I don't know the details.

This is in the past now, but it may happen again in the future. How can you suggest to a client that he may potentially be colourblind, without this person taking offense?


  1. All clients are high-paying business-owners.
  2. Most colourblind people over here are aware of it, but apparently some are not.
  • 12
    "this did not go down smoothly" > What was done, just plain out tell them they're colorblind? Is the client aware now, and are they really red-green colorblind, or were there false accusations? It would be great if there was a bit more info on what happened (how the idea of colorblindness was presented, tone of voice, timing, phrasing) since that might make it a lot more obvious if the client could have mistaken it for a false accusation or helpful suggestion...
    – Tinkeringbell
    Commented Mar 20, 2018 at 13:14
  • 2
    Are you certain the client was not just as embarrassed/angry that he was wrong as he was surprised at his colourblindness?
    – user8671
    Commented Mar 20, 2018 at 13:15
  • 11
    I am not aware of what was done. It did turn out he didn't know he was colourblind.
    – Belle
    Commented Mar 20, 2018 at 13:16
  • You should get a little more detail of what was tried from your colleague- Did they even suggest the client was colorblind? Did they just say something along the lines of, "No, this is red and this is green. Are you colorblind?" in the moment? In a heated, at least to the client, debate, that could've been considered rude. But if it was addressed differently, or the word were not even mentioned, it may be different. (Taken more or less rudely.) Otherwise, as Kozaky suggested, it could've been embarrassment. We really don't have enough to know how this went wrong...
    – Kendra
    Commented Mar 20, 2018 at 13:27
  • 4
    Is color (and choosing colors) an essential part of your business, or was this just an incidental conversation? The answer for this might be very different for, say, an interior design firm (may want to pick colors that appeal to the colorblind client, even if they don't work for people with different vision) versus a web design firm (need to pick colors that work for the widest variety of viewers) versus an accounting agency (may want to sidestep the issue altogether).
    – 1006a
    Commented Mar 20, 2018 at 17:36

8 Answers 8


I am going to slightly challenge the frame of your question, in that a more useful way to think about this interchange is to focus on it as professional handling of a difference of understanding rather than the discovery of the client's colour-blindness.

You have stated that:

The client got frustrated because he was thinking my colleague was joking with him.

I think you are probably correct that the client was frustrated, rather than merely angry. Frustration is the enemy of clear communication and the state of being frustrated is defined in Chambers Dictionary as

a feeling of agitation and helplessness at not being able to do something.

and Wikipedia notes that frustration:

originates from feelings of uncertainty and insecurity which stems from a sense of inability to fulfill needs. If the needs of an individual are blocked, uneasiness and frustration are more likely to occur.

and something that may result in

reaction against perceived oppressors or enemies

In this instance what the client needed was to understand why your colleague was insisting something was true when the client's own eyes told him it wasn't. And your colleague... well he was experiencing the same thing. Each person was telling the other that the evidence of the other's own eyes was not to be trusted. In the absence of a disinterested party to adjudicate there was no obvious way to break the logjam and they got into an unpleasant situation.

If such a situation were to arise again, however unlikely, once it becomes clear that the perceptions of the two parties are at odds and their stance deadlocked, then the person in the professional role should seek to break the impasse and try to ensure that the client does not feel disrespected or denied control.

A way to do that would be to pause the discussion and try to do these things, while keeping a professional tone and avoiding communicating exasperation:

  • Recognise that there is a difference in understanding

    I'm going to pause this discussion, because I can see that we are at odds on this and I think we need to step back and review

  • Validate the client and reassure him that there are no shenanigans afoot

    I can see that you are speaking with conviction, and I can assure you that I'm engaging in this with all seriousness and respect and am anxious to work out the problem.

  • Recap on the situation, reinforcing where opinions haven't diverged, up to the matter on which you differ.

    So, where we've got to...I've presented our proposals to you and we've agreed X.Y and Z. Now we've come to discussing the colour of items A and B...

  • Outline the thing on which views differ, without attribution of 'you say/I say'.

    When it comes to A and B, we seem to have a genuine difference of understanding about the colours.

  • Place the control of the means of resolution in the client's hands

    Should I call in a colleague to try to resolve this, or would you like to take the materials away to discuss with [someone outside] and we can get together again on this tomorrow?

Obviously there are a million ways that a conversation can go, and the dialogue presented is merely 'for example', people should use words and phrasing which are appropriate to them and their situation. But my own experience in 30 years as a practicing professional is that there is an onus on any professional to look for a constructive way forward in a meeting with a client. However, there isn't an onus on them to break it to the client that they have a perceptual deficiency.

Coming to terms with a deficiency of your vision is likely to be a very personal thing, even if it doesn't cause a change in the person's life. Even though they've been living with the condition all of their life, finding out may be a very emotional experience as it may strike at the heart of their perception of themselves, unleashing a cascade of realisations about previous interactions. You might steer someone towards the issue, but you shouldn't force awareness on them in a situation when it is at odds with their role in that setting.

An optician or doctor can tell them in a medical setting, a friend or family member might tell them as an equal... but a relative stranger in a non-medical setting shouldn't take it on themselves if avoidable.

  • Out of curiosity, why do you prefer the Chambers dictionary?
    – Ooker
    Commented Mar 21, 2018 at 1:31
  • 2
    @Ooker I don’t always, but I can use it in a phone App, rather than needing online connectivity and my 14 digit library card number that I don’t always have to hand, as I do for the OED. I also find that sometimes Chambers feels closer to English, as I speak it, where the OED can be precise to the point of confusion. As a general point it also has better coverage of Scottish English due to its origins.
    – user9837
    Commented Mar 21, 2018 at 7:25
  • 2
    I can see that you are speaking with conviction, and I can assure you that I'm engaging in this with all seriousness and respect and am anxious to work out the problem. The use of "anxious" here sounds a bit off to me (though I admit english is not my first language, I may just never encountered this use of the word). Couldn't it be better substituted by another word like "eager" or "keen"?
    – xDaizu
    Commented Mar 21, 2018 at 12:56
  • 5
    @xDaizu In case you're interested, the sense I'm using 'anxious' in is this one, as per the Oxford English Dictionary, 'Having a strong desire for something, to do something, or that something should happen; keen, eager, greatly concerned.' so you were spot on with your alternatives. :)
    – user9837
    Commented Mar 21, 2018 at 13:49
  • 10
    Wow. I wish this kind of communication came more naturally to me. I appreciate greatly your sample dialog. It is an excellent example, in my opinion, of how to proceed in such a situation professionally. Your words don't force things to an unnecessary and upsetting head, recall to mind the progress made so far which helps shift the focus to the desire to move forward rather than being stopped on the current roadblock, and gives the person a choice about how to proceed, all while possibly setting up the situation so he can discover the problem privately with less embarrassment. Reading again!
    – Sojourner
    Commented Mar 21, 2018 at 20:05

If you are concerned about this happening again in the future, however unlikely it could be, a possible approach would be to get some second opinions from both sides. If, for example, you're discussing the design of something over a web conference, you could say something like "We can see the picture here but it looks more green than red. How does it look on your end?"

If they press the issue and insist the colour is as they perceive it, maybe suggest asking them to check with someone else on their end or try displaying it on a different computer. This may eventually help them realise it on their own, or at least, it could be someone closer to them that brings up the suspicion first.

For a diagnosis such as colourblindness, it can oftentimes be embarrassing to discover this if it is due to a mishap at work or school. I knew someone who did not realise he was colourblind until late into high school (and his favourite subject was art class). The embarrassment can be just as bad as the diagnosis. Unless the colour of your item is crucial to its function - like for example, a traffic light - then it is best to give the other person an opportunity to realise this on their own, especially in a business setting. If it is someone you are close with, a more direct approach could be possible (and probably appreciated in retrospect).


The first part of your question is fairly easy; the second part is nearly impossible. It's very difficult to predict how people will respond to situations.

There are some ways, however, to reduce the chance of offense. First of all, getting into very entrenched positions in a meeting makes for hot feelings and suggesting that there's something "wrong" with the person writing you checks will, as you guess, not go well. In this case, you have to determine what you want to do. Do you want to advise the person that they might have a vision problem? Or do you want to convince them that the two items are indeed different? I'd suggest the former.

If you go that route, then accept their position that the two items are the same. Let feelings cool down and keep them from getting too hot. Remember, you want to keep the relationship and not be right. Then, afterward, I'd suggest a 1-1 meeting with the person in question. Keep in mind that you aren't a medical professional; you can only comment on things that you observe and participate in. Then I'd suggest saying privately something to the effect of, "What colors do you see these two as? I ask because I know someone who tells me "gray" or "both are the same". He's red-green colorblind and I wanted to privately let you know."

It's always risky getting a diagnosis from someone who's not a medical professional so I'd try to stay away from telling someone that "hey, you're colorblind". I'd do my best to have the message be "You might want to have that checked out". Also, try to not have the message be interpreted as "we disagreed and it's because there's something wrong with you"; that will have a bad impact on your business as a whole.


Just for a moment consider someone who is completely blind. They are of course aware of their blindness, but that awareness does not remove the problems that their blindness will bring.

My point is that someone may know that they are colourblind but they will still encounter situations like you describe.

So first of all, if you find someone telling you that two items are the same colour when they are not, don't assume that they aren't aware of their colourblindness. Secondly, be aware that they may still find the situation embarrassing.

You will only make things worse by not addressing the issue - for example if you pretend that two colours are the same, you are being dishonest and this may well backfire somehow. Honesty is the best policy.

Perhaps a less aggressive way of telling someone that two colours are different would be to say:

"I can see a difference, but perhaps it is subtle."

If they are colourblind and aware of it, this may gently make them aware that they are facing a situation where their colourblindness prevents them from seeing a difference. How they respond to the situation is entirely up to them - they may be honest with you, they may not.

I also do not feel this is a dishonest response - it is accepted that everybody may perceive colour slightly differently. You are just following the age old adage that the customer is always right.

And if they are unaware of their condition (which you acknowledged must be rare), this gentle suggestion may prompt them to ask someone closer to them for an opinion on the matter. It is after all not your place to diagnose a client's sight issues.

  • 17
    Isn't it as dishonest to suggest that the difference between red and green is subtle as it is to suggest it is non-existent?
    – user9837
    Commented Mar 20, 2018 at 16:34
  • @Spagirl I addressed this in the answer.
    – Astralbee
    Commented Mar 20, 2018 at 20:53

Hmm. Because you did not ask this at The Workplace, I take it that you are not concerned with how to interact strictly so as to maximize relations with the person as a customer and as a client of your business.

Your question here, then, is obviously how to interact with anybody in a situation where they disagree with the claims of others, and in which you think that differences in capability of perception play a part in the conundrum.

Your colleague said that the two things appeared as different colors. One person claimed that they were.
Hold it right there: Why was it so important that your colleague prove their own claim over the other? If this were limited to concerns for the sake of business, then obviously the colleague would be considering such things as

  • delivering a product — or consultation, or whatever it is that they do — which meets the client's immediate desires.
  • delivering a product which delivers on whatever they promised via contract — if they guaranteed that something would increase the client's profits by at least a certain percentage, et c.
  • ensuring satisfaction and retention of existing customers.

However, although all those are valid concerns for you, it seems that you have a more humanitarian desire: if the person cannot perceive something which others can, then you'd like them to know.

I don't mean this to be taken as Subjectivism or Existentialism, but all your colleague knew was that, in a certain environment, the claimed perception of one person disagreed with the claims of two others and that those two claims agreed: two versus one.

First, did your colleague ask the client whether they cared to pursue the matter?
Or, did they press ahead regardless? Was the client simply getting impatient, or what? Maybe the client didn't really care.

If they do care …
Would you offer to change the lighting, or to switch positions, or do anything like that? Would you remember to suggest that everybody perceives colors differently, and that it usually doesn't even get noticed unless two people are discussing industrial or creative matters which concern certain colors.
In various scientific, industrial, and commercial disciplines, color conformity and consistency are very necessary. Anyone who works in printing or graphic design knows this.
However, it seems to me that the only purpose for which you have any cause to be excessively concerned is that of safety.

As it happens, although an inability to distinguish the colors which most people know as Red and Green has been documented in modern, so–called Western Culture since the 1800s, there are a few places where the ability to perceive and distinguish such colors is expected and required: general aviation; roadway automobiles; naval aviation.
As an aside: There are many places where colors are either not important or are simply used as one in a set of many environmental cues. The lights above locomotive i.e. train tracks don't rely on color; in power plants and similar industrial environments, the colors of electrical wiring, pipes, the operators or handwheels of valves or switches, and many other such things are often helpful when distinguishing objects but are never to be used as the sole methods of identification. Furthermore, I've read somewhere that certain forms of so–called “colorblindness” allow the brain to better develop its ability to perceive and recognize patterns and shapes — so, not every disability is a disadvantage.

That's really all there is to it. If you think a person is red–green colorblind, and your concern is for their safety, and you are prompting the question, then you want to consider three things:

  • the person's sense of certainty.
    Remind them that everybody perceives the world differently, and that our lives are simply a matter of discovering how to interact with our perceptions. Do you have reason to believe that the person deals with anxiety or paranoia? See to the next point …
  • the person's trust in others — not necessarily you, but perhaps a common friend or in those of the medical profession.
    See the above point: in addition to sensory perceptions, we also have the perceived interactions with other people. Some of those we learn to trust — some we learn to distrust. Same reasons.
  • whether the person has ever considered or tested themselves for something similar.
    Tests are very simple and rather easily available. There is that well–known one of the numeral hidden in the bunch of dots.

Unfortunately, because you ask a question of a possible future interaction, that is the best guidance which I can think to give you.


More context could help. From one point of view, the purpose of beliefs in to predict future events. What events does "These are different colors" predict versus "These are the same color"? Possibilities would be "Other people will claim they are different colors", "Other people will be able to tell the difference between two objects of these colors", "Other people will have different reactions depending on which of these colors are used". One thing to notice is that these all have "other people" in common. Color is a qualia, and you were implicitly asserting "These two colors generally generate different qualia". This is not a matter that can be settled in a discussion between you and the client, at least not if the client doesn't trust you, and suspects that you are playing some sort of prank.

So when talking with the client, the key points would be: 1. These colors generate the same qualia for you (the client). 2. These colors generate different qualia for me. 3. I acknowledge your experience of the colors generating the same qualia, and ask that you show me the same respect of accepting that they generate different qualia for me. 4. If you are having trouble doing so, you should consult people you trust. (Although if you have two objects that the client insists are exactly the same, then you could just turn your back and have the client rearrange them, and then show that you can distinguish them. This could be overly confrontational, though.)

There is then the issue of why it matters. If you're designing a user interface, and the client says "These two colors are the same", and you reply "Only a colorblind person wouldn't be able to tell the difference", well ... do you not want your interface to be accessible to colorblind people?

On the other hand, suppose you've tested out Color1, and found that customers find a store painted in Color1 to be pleasing, and the client wants to paint the store Color2, and insists that it's the same as Color1 and therefore customers will find it pleasing. Now the issue is whether Color1 and Color2 have the same effect as to customer satisfaction. So the focus should not be on whether you or the client perceive them as different colors, but whether customers do. Instead of focusing on "I think you're colorblind", you should focus on "I think that customers will make color distinctions that you do not". Now of course the issue of whether the are the same color is going to be relevant to that question (if they are literally the exact same color, then customers can't possibly have different reactions to them), so if your client is insisting that they are completely indistinguishable, then you'll have to address that, but your main focus shouldn't be on whether it's "objectively true" that they are different colors, but whether customers perceive them as such. So a possible response would be something along the lines as "I don't think we're going to get any closer to a resolution simply by discussing this further. How about we find some customers and see what they think?"

So you should ask yourself "What are the practical implications of this disagreement?" and focus on addressing those, rather than fighting over labels like "colorblind".


According to Google, colorblind means this:

  1. unable to distinguish certain colors, or (rarely in humans) any colors at all.

The problem with this scenario is that 'colorblind' is a huge misnomer (in one sense of the term). Most colorblind individuals can actually see a great deal of color (many can see most of it, in fact). However, they may not see enough of certain colors to be able to pinpoint exactly what a particular one is. Like, they might not see a certain kind of sea green very well, but forest green is plain as day—stuff like that. I can see pretty much every single color in cartoons very easily, but many car colors and clothing colors are quite difficult by comparison. The size of the colored object matters. The distance also matters. The light levels also matter. How dark or light the color is matters. I can see some colors easily in some situations, but I may not see them at all in others.

Anyway, you need to acknowledge that your client really can see colors—unless he's one of the extremely rare people who really can't see any. If you just say he's colorblind, he'll feel like you're picking on him, labeling him, misunderstanding him, etc., even if (and perhaps especially if) you prove it to him with a colorblind test without validating him first—that can actually be traumatic, and I've seen people be in denial about what their test results mean (a relative and a roommate of mine).

You need to recognize that your client's perceptions still have value in the real world even if he's colorblind. You can't just write him off as colorblind and say his color-vision doesn't matter anymore, and not just because of the misnomer: Colorblind people are actually capable of seeing some colors that cannot be perceived easily, if at all, by color-normal people. For instance, if an object is a mixture of red and blue, but doesn't have very much blue in it, someone with red-green colorblindness may notice the blue in it easily, while a color-normal person will probably think there's no way there's any blue in it (unless they're used to adjusting RGB values on websites or something and aren't into inductive logic). So, when they say something looks like a different color, that doesn't mean they're wrong, per se (at least if they're not just guessing what color it is, but they actually see it that way). What they see exists—they're just not seeing everything. It's kind of how white contains a lot of red, blue, green/yellow, but you can't really see any of those colors in it, unless you take some color out of the picture. If yellow is the only color you can see, white will look yellow (because there is yellow in white).

Anyway, the definition of colorblind is also flawed, because there are colors that most humans can't see (but somehow, that doesn't make most humans colorblind, while if you can't see a few rare kinds of red and green, somehow you are colorblind). For instance, most humans can't see UV or infrared, but some people can, and birds can, too. Does that make everyone else colorblind? It's a double standard to say that because you can see these colors, but not those, you're colorblind, when color-normal people can also see colors from some wavelengths, but not others. I don't know anyone who can see colors made via microwaves, but I'm sure they exist.

Anyway, I think you need to make the person feel like you're being fair. You need to acknowledge their capabilities (that they haven't been completely delusional their whole life), and let them know what colorblind really means. (It doesn't mean you can't see any colors—nor does it mean that the person should be treated as if they're inferior. It might also be worth noting that some colorblind people are not affected by camouflage.)

I believe you should also recognize that just because your friend with red-green colorblindness can't see a certain thing, that doesn't mean that your client can't. There's usually a lot of variance between two people with colorblindness.

Also, be careful, because your client might not be colorblind at all. It's possible he was just starting at some bright color that temporarily blinded him to the color at hand. I know if I stare at a certain kind of bright pink (which I can see) for a short while, and then look at other things, the colors look different for a time. There may be other scenarios like that.

Also, realize that colorblind people are sometimes actually already aware that they have trouble with certain colors, but they don't realize that this makes them colorblind. They may think everyone has such troubles, or that it's not significant enough to make them colorblind. However, they can gain a lot more insight into what color is what if they know they're colorblind and admit it (this is my experience, anyway).

Anyway, so for my answer, I'm going to have to say, be sensitive to the situation with the things above in mind. It's not easy to convince someone they're colorblind—but if you're going to do it, at least make sure that everyone concerned knows what 'colorblind' means first, and that it's a misnomer (they usually don't). Don't gloat. Don't remind the person that they're colorblind at the slightest provocation thereafter. Don't talk about how you can see more colors than they can (and do realize that if you haven't been tested, you might be colorblind, too, even if you can see those colors that your client can't). Please do not unnecessarily reveal the person's condition to every Tom, Dick and Harry in their presence, even if they're not in denial about it (but especially if they are).

I know a lot of these things I've said not to do are tempting, and I've done some of them myself (which I shouldn't have); but, I'm not trying to condemn anyone for having done such things. People make mistakes, but we can all move on, learn, and become better.

Treat the client respectfully. Treat the client as an equal. Things might not go so smoothly, but it's not the end of the world. As long as you're respectful, I don't think they'll hate you. They may be in denial about it, or not like/believe what they hear, but if you don't otherwise offend them, they may be more likely to one day be glad you told them—and it probably won't hurt your relationship. However, if you rub it in their face that they're colorblind and act like they can't see any colors, then they're probably not going to want to deal with you so much.

If you don't have a legitimate need to convince someone that they're colorblind, from an interpersonal relations perspective, I agree with others that it's probably best to leave that to the professionals (or the individual themselves).


tl;dr- Use a color model as a reliable reference, then discuss their preferences in terms of the color model. Whether you should actually use the term "colorblind" or even discuss their difficulties in perceiving color will probably be highly situational.

1. Use a color model

Computers describe colors in clear, digital format, e.g. the RGB color model which describes colors in terms of a selection of three primary colors: red, green, and blue. This creates a commonly accepted basis for analytically determining what colors are and comparing colors.


  1. Get the colors in digital format.
    If you already have an image with the colors in it, you're set! If not, then you can either use a digital camera to snap a picture (if the color is in the physical world) or use a screenshot/screen-capture tool (if the color is in the digital world).

  2. Get the colors' data.
    This question on SE.SuperUser shows a few methods. For example, opening the image up in Paint on a Windows computer and then using the "color picker" tool is pretty quick and easy.

  3. Look up the colors' names.
    A lot of websites (e.g. 1, 2, 3, 4) can help convert from color data like RGB to a color name. You may want to check a few different sites as the precise names that they provide may differ a bit.

  4. Compare the colors' data numerically.
    If using RGB, then if you have two colors, [100,100,100] and [150,200,0], then it's pretty obvious that they're not the same thing. It's probably not the case that RMS-distance over the color space of any given model well-corresponds to perceived differences in a typical human's vision, but significant numerical distance should still significantly reinforce the idea that two colors are different.

  5. Provide them with a quick summary-and-verifiable of the colors' names and data.
    Personally I'd think to do this in an email with screenshots of the colors being sampled from the image source (e.g., in Paint) to show them the color data being retrieved, then links to the online resource that you used to get the color names from. Ideally, this would be very simple and readily verifiable.

This has a few advantages:

  1. It's no longer just your opinion.
    Now they don't have to believe in your opinion, but rather can refer to authoritative references for color names. If you suspect that they might be especially dubious, you could link a few different sources of names. And if they still have any doubts, they're now in a position to investigate it themself, both empowering them and removing you from the range of those that they're in a state of disagreement with.

  2. They have a basis for understanding and discussing color.
    Now that they've seen how to measure colors, look up their names, etc., they have a methodology for discussing the topic in clear, analytical terms.

  3. It's a cleaner, more precise form of communication.
    For example, they can select a specific color from a color wheel and refer to it by its RGB value without stressing over how to refer to a color's name or worrying about being unclear.

2. Discuss objectives based on the color model

Now that the colors' data and names have been clarified and there's a precise color model that can be used, you can consider what your objectives are in interacting with the potentially colorblind person.

To steal @1006a's comment:

Is color (and choosing colors) an essential part of your business, or was this just an incidental conversation? The answer for this might be very different for, say, an interior design firm (may want to pick colors that appeal to the colorblind client, even if they don't work for people with different vision) versus a web design firm (need to pick colors that work for the widest variety of viewers) versus an accounting agency (may want to sidestep the issue altogether).

So if you're designing a website, you might be more inclined to enter into a discussion about different people perceive colors since it'd seem potentially relevant to how the website's color scheme should be selected. Still, the focus should probably be less on "you're probably colorblind, go get checked out!" and more on how potential site visitors are likely to perceive the colors.

In that case, you might still discuss the topic of colorblindness, but with respect to site visitors. For example, it's often advised that people making data visualizations avoid reliance on colors that're frequently similar in the view of common colorblind conditions.

Alternatively, if you're selecting a color scheme for the wall paper in someone's personal bedroom, then there'd seem to be less motivation to talk about how their color perception may differ from the general population's and you might simply focus on selecting what they enjoy. Here, you might ask them to help you identify their color-contrast preferences, playing down what might be called "colorblindness" as a variation in personal preference.

3. Obligatory xkcd

Since color perception can vary significantly from person-to-person, including between sexes, it may be helpful to discuss the topic with people even if they're not potentially colorblind. xkcd did a color survey:

And apparently here're the color name boundaries determined from a large sample of the population:

Folks who're in a business where understanding color perception is important might do well to read up on stuff like this study. Then if it's important to discuss the topic with clients, having references to this stuff can help facilitate discussions with clients.

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