The poor user experience of microwaves has always bothered me and I took the opportunity to tackle the issue as part of a group project at the University of Washington.
The efficiency of a microwave interface is simple to benchmark: how many button presses does it take to enter in the correct amount of time? The traditional input system of entering in a full minutes takes 4 button presses: 1, 0, 0, start. Most microwaves offer a “+1 minute” express cook button, reducing the number of button presses from 4 down to 1. Many microwaves also have a grab-bag of preset cook times, which offers similar theoretical efficiencies. We wanted a unified theory of these different input modalities and questions around their actual usage determined our research agenda.
We performed 7 in-situ observational studies of people using the microwave as part of their daily routine, followed by structured surveys. Ages ranged from 18-50, and the sample was a mix of students and working professionals.
Despite a seemingly diverse mix, we found that the core microwave tasks revolved around reheating leftovers or preparing pre-cooked meals; few ever used their microwaving for defrosting or cooking meals. Only one participant used the presets that come with almost every microwave and even then it was only for popcorn.
While we suspected that few participants would use the preset functions, we were not sure what reasons would be given. Most participants expressed frustration about the presets over or under heating their foods. For example, participants who did not use the defrost feature generally cited incidents in which part of their food was cooked while other parts were still frozen.
“It’s not a precise science. A lot of times it’s trial and error. You’ll put things in and it’s not right; either over or under cooked.”
We followed up the observational studies with an online survey of 42 participants. The survey consisted of multiple choice and short answer responses. The responses largely reinforced our previous findings – few participants ever used the preset cook settings and many complained about the number of excess buttons.
However, unlike in our observational studies, participants did more than just express a preference for exact timings. Multiple respondents pointed out that microwavable popcorn bags warn against using the presets. Others noted that the presets just didn’t make any sense.
“Sometimes the automatic settings are for foods that make no sense. Like baked potato or frozen vegetables. Why are they so special?”
The participants’ most frequent complaint was how loud their microwave was. While we had heard this complaint in our 1:1 interviews, we were surprised at their level of frustration and at the suggestions offered:
“… the LOUD beeping!! Really?? Would like a mute option so I don’t wake up everyone in the house when I want to heat something up.”
“More customizable beeps and bloops. I usually dislike the noises microwaves make. I’d like the option to turn it off COMPLETELY, or change it to something silly like the Saxophone riff from ‘Sax Gandalf.’”
The qualitative research also surfaced complaints associated with defrost presets rooted in experiences of uneven re-heating of frozen foods. Many complained of partially cooked meats and advanced users reported that they needed to break up frozen foods as it was defrosted.
Multiple Choice Surveys
Having identified trends in usage, it was time to validate our data. Given the near universal presence of auto-cook functionality we worried that our convenience sampling methods had limited us to middle-class users with different cooking habits than the rest of the population.
We sent an online survey to over 1000 people, asking which auto-cook settings they used, if any. The responses were weighted by income to represent a statistically representative sample of the population.
- 45% Never used any auto-cook settings
- 30% Popcorn
- 20% Defrost
- 15% Reheat Leftovers
- 7% Water
- 7% Vegetables
We also wanted to nail down how many people used exact timings vs express-cook (+1 minute or +30 second buttons). We were less concerned about the impact of economic status on this survey and we sampled 300 Amazon Turk users. It turned out that 30% of respondents used the express-cook buttons almost exclusively, while 20% used only exact times and 50% used a combination of both.
After gathering data, we created personas to represent the use-cases we found in our research.
Despite being a busy PhD student, Kathy takes care of herself. She knows how to cook and she drinks a lot of green tea at the research lab. This limits her microwave use to reheating leftovers and zapping mugs of tea at work.
I’ll use it to defrost, but only when I’m short on time. I think that hot water works better, because it’s slower and does not cook the food. Sometimes using the defrost setting is really uneven; like half of the food is cooked and the other half is still partially frozen.
I would like a mute option so I don’t wake up everyone in the house when I want to heat something up. One thing that really annoys me is the beeping. Some nights, I’m trying to pull an all-nighter and it beeps really loud while everybody is sleeping, even if you open the door before it finishes! I wish that there was a way that you could set it so it wouldn’t beep when you press all the buttons, and maybe just once at the end. I like when microwaves beep when you open the door, but like I said this one is a preset amount, like 6 beeps, and it doesn’t stop when you open the door – it keeps beeping until 6 beeps have been completed.
I burn popcorn in the microwave about 90% of the time. It makes me a sad panda. I don’t really use express setting because I’m the type of person who likes to do other things while I’m microwaving something, even if it’s just for a couple of seconds. So if I only want to cook something for 20 sec, but I can only hit the minute express button, I’ll forget about it, and it will be over cooked. Like on the microwave at my work, I can’t figure out how to use it without the express buttons, so I have to make sure I’m there, watching it, all the time. It doesn’t work out when it comes to popcorn.
Brian uses the microwave a lot. When we say a lot, we mean he eats at least one frozen meal a day and he unfreezes them in his most trusted kitchen appliance: the microwave. It’s not that Brian is lazy or stupid, it’s that he doesn’t want to spend the time, energy, and money on learning how to cook. He gets most of his food from Trader Joe’s, Amazon Fresh, and the farmers’ market. He once dirtied some pots and pans to convince a date that he had cooked everything himself.
I need to know a preset will work before I use it. It’s not as customizable as I expect it to be from the number of settings it offers. It’s easier for me to input stuff manually, because I get more security from doing it myself. I wish it were more sophisticated.
I don’t know what I’d do without the +30 second button. I like the +30 second button because it’s a few steps faster. Even if I’m only needing it for like 10 seconds I [push +30 seconds] and just stop it early.
Kevin is a stay-at-home dad who (as he puts it) does “part-part-time” consulting work. He loves working on the house when the kids are at school but he really enjoys doing activities as a family. He chose his microwave after checking Consumer Reports, Cnet, and Amazon reviews. He is meticulous because he is a geek and it’s one of the few tech items he can afford to buy.
I need a microwave that cleans up after exploding soups! I’m not sure what it would be, but anything that would make cleaning the inside easier would be great. With two kids, the insides are always … extremely unpleasant to look at.
Less sauce explosion, more even cooking. I wish it knew automatically when food is cooked, or at least knowing when to stop if food is being over cooked. I would like to just put something in and walk away, without even having to thinking about it.
I want more customizable beeps and bloops. I dislike the noises microwaves make. I’d like the option to turn it off COMPLETELY, or change it to something silly like the Saxophone riff from Sax Gandalf.
Most microwaves waste roughly half of their surface area, so we decided to silk-screen the UI atop adjustable opacity glass. This allowed us to stretch the interface across the entire door of the microwave. After extensive paper-prototyping, we decided to embrace the dial-pad UI of existing microwaves for the primary UI, as more radical departures frustrated users. However, the extended space allowed us to create dedicated input modalities for both express cook and defrost.
The primary contribution was a dedicated section for express cook timings, covering the most common cook timings used instead of a single “+1 minute” button. We decided to consolidate preset cook times into a single sensor based cook button and augment it with a barcode scanner, so cook times for pre-packed foods could be fetched from a database.
We also dedicated a section to defrost, replacing the clunky weight calculation with express-style settings and a sensor mechanism. Part of this departure was driven by the assumption that better engineering would lead to better automatic defrost, such as using 3d scanners to detect hotspots and 915 Mhz waves for deeper penetration and more even heating.
We also focused on the user experience of cleaning the microwave. After a few rounds of ideation, we settled on a silicone insert for the inner cavity and a removable glass panel for the door. The silicon would be seamless but have creases so it could be folded to fit more compactly in a dishwasher. But what about the little spinning plate in the middle? After speaking with an engineer, we found that the spinning plate in the middle of a microwave is a gimmick. We can evenly distribute the microwave beams around the inner cavity using rotational wave guides.