Mother sometimes has a fifth appendage, the lunge whip. She has two different ones, the red one I've always known, and a creepy black one that's not quite the same. I've see her with other appendages, which she uses around other horses, but she pretty much only uses the red appendage for me.
She can make the whip make sharp sounds, and this reminds me to move along again... like when she would let me gallop loose in the large arena at the old barn on snowy nights, because I needed "more exercise". That's winter fur, not fat, lady. If I stopped for too long, that sharp sound would remind me to keep moving.
When she lunges me, I keep an eye on the whip as well as listening to Mother's voice, to know how quickly I should be moving. She seldom has it make sharp sounds when she lunges me.
When she ground drives me, she wraps the noodly part of the appendage around the stick part and will use it to touch me on my sides or rump to indicate motion or direction changes (or, sometimes, just a touch to remind me she's back there and she made a request... I get distracted way up there all by myself, and forget she's back there). This is where she sometimes uses the creepy black whip instead. She also has black lines to drive me with. She says they look nicer than my dirty, dingy white lines. I don't like them though. I like my red whip and white lines.
Sometimes when she props the whip up against the wall, it leaps to the ground. I don't let this bother me, because as it's Mother's appendage, it won't hurt me. I know some horses who are afraid of whip appendages, because they say they hurt. I will admit I've watched wide-eyed as Mother has wielded her appendage at others with more force than I think she uses with me, but it's never hurt me.
The other day, we walked into the barn after driving. I was turning around in the hall, when the appendage brushed my front legs. WHAT!?! I froze... peered, snorted.... why would this touch my legs? I need my legs! It's never touched my legs. Mother apologized and said she didn't make it do that, the hall is tight and it just happened, the same way it sometimes just falls from the wall.
While it didn't hurt me... uggg, that was just creepy. No wonder some horses don't like these things...