Vivofit 4 registers steps when I'm petting my cat

It is just arm movements. Nothing else. 

There is a threshold of 10 movements before it starts to count. 

Pet cat with your other hand, OR sign up for bigger step challenges and make the cat happy.... :)

2105489 said:

I thought the watch would use more cues than just arm moment.

Which ones for example?

BTW, it is not just the arm movement, it is any acceleration the watch can detect. If it can detect rhythmic acceleration curves with the frequency matching the range steps normally trigger, they will be counted as steps. You can keep your hands in the pockets and jump, not moving the arms at all, and you'll still get steps. You can shake a cocktail mug or brush the teeth, and you'll get more steps. That's how it works. If you do not want any false steps at such activities, either remove the watch, or start a dummy activity blocking the steps counting (i.e. Indoor Cycling) and stop & discard it at the end, when you want to resume with the counting.

To answer your question, I had assumed a combination cues are needed to register steps, such as arm movement and horizontal movement over ground etc. That could help avoid false counting.

To constantly remove watch would be annoying. This is a pretty inaccurate instrument it seems 

Not an exact science as everyone has different running/walking styles. Other manufacturers experience the same issue. Either not registering enough steps or too many steps 

 Petting my dog is adding steps - Fitbit Community

Apple Watch counts too many steps at the office - Apple Community

2105489 said:

such as arm movement and horizontal movement over ground etc. That could help avoid false counting.

And what about walking / running on a treadmill? Or walking on place? There is no horizontal movement involved. Besides that, you cannot detect horizontal movement with an accelerometer alone. You need also a gyroscope which can detect the orientation of the device in the space. However, not all Garmin watch models have a gyro. Specifically Vivofit 4 does not have any, so there is no way the device could give any data on the speed or on the direction of the motion. All it can do, is detecting the bumps (acceleration peaks), and count them as steps.

Good points. Thanks

Has me reconsidering the value of these gadgets 

2105489 said:

I wonder if the old waistband pedometer technology is more accurate

It should be. As well as the watch would count the steps more accurately if worn in the pocket.

2105489 said:

We're now wondering how many of those are from chopping with a knife.

If she wears the watch on the other hand, then the difference will be negligible. Accidental hand movements will be filtered out. Only repetitive movements with certain intensity and in given frequency range will be counted. Also the number of the detected "steps" must reach ~20 before being added to the steps counter.