Why can't Godfrey work the trackpad?

May 15, 2008 8:50 PM

Why, when I drag the fleshy (i.e., not furry) part of my cat's paw across the trackpad on my MacBook, does the cursor not respond?

No, seriously.
What is it about the difference between his paw and my finger that makes the cursor move?

No cats have been harmed in the formulation of this question.

posted by Dr. Wu to computers & internet (35 comments total)

They work by sensing the human operator's soul.

Seriously, though, it's explained on Wikipedia. I don't really get it, though.
posted by Mr. President Dr. Steve Elvis America at 9:04 PM on May 15, 2008 [3 favorites has favorites]

Try dragging something larger than the tip of your finger across the trackpad. When I do that to my MBP, it doesn't respond. The pad depends on a small locus of input.

(I liked the first answer better, though).
posted by Dipsomaniac at 9:04 PM on May 15, 2008 [1 favorite has favorites]

His paw pad isn't moist enough. I have the same problem w/ my trackpad, however, I'm not a cat.
posted by jamaro at 9:06 PM on May 15, 2008

Touchpads take advantage of the fact that the human is a capacitor. Since a cat weighs far less than a human, it will have a much smaller capacitance and will fall below the activation threshold for the circuit.
posted by Class Goat at 9:06 PM on May 15, 2008

jamaro: In that case, how come I can use the trackpad with my knuckle or my elbow?
posted by danb at 9:07 PM on May 15, 2008

My cat's paw moves the trackpad on my iBook. Maybe it's just more sensitive than yours.
posted by loiseau at 9:15 PM on May 15, 2008

(The trackpad, not the cat.)
posted by loiseau at 9:15 PM on May 15, 2008 [26 favorites has favorites]

danb: it would be impolite for me to speculate why you have oily knuckles. Excessively dry hands + trackpads are a PITA, though I can't maintain they are the only reason why a trackpad would not work.

For small values of interest, I have the same problem with fingerprint scanners. I have to lotion up before they register my touch.
posted by jamaro at 9:17 PM on May 15, 2008

My cat's paws work too, much to my frustration. For point of reference, the computers i question are a Fujitsu Lifebook and a Toshiba Satellite; she can control both.
However, unlike loiseau, I am fully prepared to speculate that my cat is more sensitive than yours.
posted by katemonster at 9:30 PM on May 15, 2008

Not enough pressure/density/texture/moisture? This sounds like something for The Straight Dope!
posted by turgid dahlia at 9:47 PM on May 15, 2008

I'll add that my cat's paw easily operates my iPhone, no doubt due to its multitouch abilities. Since most trackpads don't have that I'm siding with Dipsomaniac, needs smaller contact point.

To add to the moisture issue, I had a ton of trouble using my trackpad in Florida during some humid summer days. No contact necessary, just hover anywhere near the pad and the cursor slides all over.
posted by bmalicoat at 10:57 PM on May 15, 2008

I just tried this with my (exceedingly patient) cat, and it seems to work with a single locus of input, regardless of size. We were able to use the trackpad using single "fingers" or with the pad, but we were not able to get any trackpad movement if there was more than one bit of input (two "fingers", or finger + pad/palm area).

I will now use his paw to navigate to and click the "Post Comment" button...
posted by stefanie at 11:06 PM on May 15, 2008 [19 favorites has favorites]

Because this is for SCIENCE, I tested my dog's paw on this Thinkpad's trackpad and it worked just fine.
posted by moonmilk at 11:21 PM on May 15, 2008 [5 favorites has favorites]

In the interests of Science, I grabbed one of our cats and tried it on the MBP. Her paw doesn't move the cursor but she can scroll pages with it, likely because multi-touch can register larger/multiple inputs.

Then she ran away. Damn Luddite.
posted by Dipsomaniac at 11:26 PM on May 15, 2008 [2 favorites has favorites]

I can confirm that the hoof of a horse does not work on the trackpad. I'm not sure why though.
posted by markovich at 11:28 PM on May 15, 2008 [25 favorites has favorites]

Try wearing a pair of gloves and trying to move the mouse on your keypad. That won't work either. I guess it needs a small locus of pressure to work.
posted by peacheater at 11:52 PM on May 15, 2008

By gloves I meant woolen mittens.
posted by peacheater at 11:53 PM on May 15, 2008

Wolfhound paws won't activate the trackpad on my iBook either. They will, however, mash leaf litter and dirt into the keyboard. The things I do in the name of science...
posted by tim_in_oz at 1:15 AM on May 16, 2008

My cat's paw works the touchpad on my Toshiba Satellite without a problem.

I recommend the experimental protocol specify a sleeping test subject and handy can of tuna.
posted by MadMage at 2:44 AM on May 16, 2008

Additional data point:

Computer: Dell Latitude X1 laptop.
Input device: trackpad.
Organism: cat, black, short-hair.
Limb: paw.
Result: Success.
Conclusion: this explains all the cat-scanner sites in my browsing history.
posted by googly at 4:33 AM on May 16, 2008 [7 favorites has favorites]

Cat resident #1, 15-pound British Shorthair tabby: cannot operate trackpads. Dislikes all computers except warm laptops that have just been closed.

Cat resident #2, 11-pound Abyssinian: can operate trackpads and mouse buttons, and is really good at turning on the horrific zoom "feature" of my wireless keyboard. Also involved in intimate nuzzle-relationships with the monitor and likes to join conference calls.

Computer tested: HP work laptop with trackpad, and the Logitech wireless input devices on an HP Pavilion desktop. If I could find the power cord to my accursed iBook, I would test Cat #2 on that, but I suspect he ate the power cord.
posted by catlet at 6:15 AM on May 16, 2008 [3 favorites has favorites]

Hi, all, and thanks for the answers! (Sorry for the delay - I posted just before going to sleep, and have only now had a moment to return to this thread.)

Godfrey is right here, tucked between my arm and the laptop, and he agreed to another trackpad-testing session, based on your answers above.

1. We adjusted his capacitance (using a Flux Capacitor, of course), and this had no effect.
2. I cleaned all oil, moisture, and Gritty Kitty™ brand kitty litter from his paws, and this had no effect.
3. BUT! When we used one of his "fingers," the cursor DID move! It wasn't a perfectly smooth movement, and it was sort of intermittent, but it did work. I think it was the "too many inputs" problem, simply enough. So it was a simple solution to a silly question, but I'm glad I posted it, as this turned into a fun thread.

Thanks!
posted by Dr. Wu at 6:36 AM on May 16, 2008 [2 favorites has favorites]

I can't wait to go home and try it with my two non-declawed cats.

I'll be sure and post an update from the ER.
posted by desjardins at 3:18 PM on May 16, 2008 [1 favorite has favorites]

Why can't Godfrey work the trackpad?

Easey-peasey. He's not a dog!
posted by ericb at 3:53 PM on May 16, 2008

Then she ran away. Damn Luddite.

I swear, I haven't been anywhere near your cat.
posted by Luddite at 4:54 PM on May 16, 2008 [10 favorites has favorites]

My dog's furry chin works on the trackpad - she scrolls back and forwards in my browser quite deliberately, when she thinks that I am spending too much time on the PC. It may be because that part of her is slobbery. I suspect that the capacitance required depends on moisture to make a contact. Try again after she has been licking her paws.
posted by Susurration at 5:14 PM on May 16, 2008

Relatedly: Why don't my kids come running when I run the can opener?
posted by DU at 6:03 PM on May 16, 2008

Thanks to Horace's curiosity about whether I could use the trackpad or not, I have now become fully conversant in the operation of his computer. I'd chat more, but I have to go "borrow" his credit card and visit www.wildpacificsalmon.com.
--Perseus (Discourse Marker and Horace Rumpole's cat)
posted by Horace Rumpole at 7:43 PM on May 16, 2008 [16 favorites has favorites]

1. We adjusted his capacitance (using a Flux Capacitor, of course), and this had no effect.

I believe its called a Fluff Capacitor.
posted by Merik at 9:38 PM on May 18, 2008 [2 favorites has favorites]

I just tried with my polydactyl cat, and she is fully capable of multi-touch gestures, which given her nature was to be expected. The non-polydactyl cat looked at me like I was fucking crazy and ran away.

I'm pretty sure that Horace Rumpole's answer was better, but I figured we needed a polydactyl cat data point for completeness sake.
posted by togdon at 9:41 PM on May 18, 2008

It relies on the electrical reaction with human skin. Try using your fingernail, flat on the trackpad. It won't work either. Kitty pads are mostly dead tissue.

(I'm splainin' this from memory of stuff I read one time in the bathroom, and reserve the right to disown this answer by saying my cat posted it from my MacBook. She uses a USB mouse.)
posted by Fuzzy Skinner at 9:54 PM on May 18, 2008

Items which cannot work my Dell Inspiron trackpad, despite having small cross section:

the end of my watch
the base of my webcam
my fingernail
a nearby allen wrench

Areas of future research:
Can a hamster turn on a touch-fan?
(Actually this is past research; my sister and I were trying to figure out how the fan worked. You touched on its grate to turn on or off. The hamster, held in insulating gloves, could not turn on the fan. I should scan in that picture...)
posted by nat at 11:10 PM on May 18, 2008

I can get the top of my fingernail to control the trackpad (iBook G4). Good to know if I develop onychogryposis.
posted by you're a kitty! at 9:58 PM on May 19, 2008

I just tried with my polydactyl cat, and she is fully capable of multi-touch gestures, which given her nature was to be expected. The non-polydactyl cat looked at me like I was fucking crazy and ran away.

Do you hear that Mefites? That is the sound of ultimate suffering. My heart made that sound when the six-fingered cat killed my father.
posted by Vindaloo at 10:59 AM on May 26, 2008

Clearly, we need to compile a gallery of people manipulating their animals to see if they work their computer's trackpads. We'll call it... pawpads.com or something that's available...
posted by disillusioned at 12:29 AM on July 7, 2008