Half an hour after the first round of introductions and ice breakers, our customer journey mapping workshop was in full swing. The five customers in my group were in the midst of a warm-up activity we often use to precede journey mapping proper—brainstorming and prioritizing the ways in which they interact with an organization, in this case a major retailer. Here’s how it works: the customers capture each interaction—each touchpoint—on a separate yellow sticky note, and then place those sticky notes on a paper continuum from “least useful” to “most useful.” Then the facilitator (that’s me!) points to interesting sticky notes and gets the customers to explain what makes that touchpoint useful, or why they hate it, or what could make it better.

The conversation was flowing well, and in my excitement, I grabbed a Sharpie and muscled my way to the front of my group. When I heard one customer describe a helpful email he had received about an upcoming sale, I hastily scrawled down the details on a sticky note.

He’d said it was helpful, so that must mean it should go under “most useful” on our continuum, right? A few minutes later, the pace of the conversation had slowed—two of my group members were munching bagels left over from the breakfast spread, one was surreptitiously checking her phone, and another was intently inspecting his shoes. I was the only one holding a writing implement. Oops.

For new and experienced facilitators alike, the temptation to over-facilitate can be strong. Maybe a customer doesn’t understand the instructions for a new exercise, so we model how it works…then forget to stop modeling. Or we mask the awkwardness of a conversational lull by taking up a pad of sticky notes and capturing the last thing we heard. We make assumptions about what customers really think—like I did when I assumed that the email about an upcoming sale qualified as “most useful.”

But the purpose of inviting customers to a co-creation workshop is not to reinforce our own assumptions about their experiences and expectations. It’s to challenge those assumptions. We want customers to respond to our hypotheses with the reality of their experience: What do they need and want from a phone call with a service rep? What type of information were they looking for on the website? How did that email notification make them feel?

A critical part of getting unfiltered, unbiased insight from customers is to give them the tools they need to express themselves—to put tangible workshop materials into their hands and watch what they do with them. So when I feel myself overwhelmed by the desire to take up sticky note arms and charge to the front of the group, I perform a simple thought experiment:

I pretend I have T-Rex arms.

Someone with T-Rex arms can’t write with a Sharpie, and she certainly can’t put a sticky note up on the wall. T-Rex arms can’t reach! When I’m mentally wearing my T-Rex arms, I remember not to scribble down what I’ve heard and then assume I know how important it is to a customer. Instead, I hear email about an upcoming sale and I say “Great! Capture that for me on a sticky note!” When the customer tries to hand me the sticky note he’s written, I say “Awesome! Now where does that go on our continuum? How useful was that email?”

Having T-Rex arms doesn’t stop me from asking follow-up questions. “What made that email helpful? How could it have been MORE useful? What would a ‘most useful’ email look like?” But it does stop me from squeezing the customer’s feedback or idea through my own filter or misinterpreting how he felt about a particular experience. Later in the exercise, we circled back to that sticky note about the upcoming sale email and it turns out I’d gotten it wrong. “Sure the email is helpful,” this customer said, “but only if I read it, and most emails like it go straight to junk mail. It’s not nearly as useful as the push notifications I get on my app.” I would have missed that key insight entirely if I had trusted my own assumptions.

If you’re lucky enough to spend time with your customers in a workshop setting, make the most of it by relinquishing control of the writing implements. Give clear instructions, then step back and watch what your customers do. Instead of looking to you for validation, your customers will feel empowered to be descriptive, creative, and frank.

One of my proudest moments as a facilitator was later in that same workshop, after I’d course-corrected by donning my trusty T-Rex arms. I charged participants in my group to create a mock-up of their ideal retail website—I pointed them toward the pile of poster board, stickers, scissors, and tape, and then I sat down. For the first agonizing minute-that-felt-like-an-age, awkward shuffling and shrugging ensued. I had to sit on my hands to keep from grabbing the supplies and prompting them.

As my group realized I wasn’t going to do this for them, the inevitable miracle happened: one customer picked up a marker and started sketching. The others clustered around her in growing enthusiasm: “What about the calendar we talked about?” “Can we make a page for upcoming events?” “We can make the checkout process easier—let’s add a progress bar!” My group’s creative ideas were music to my T-Rex ears.