The question in this situation is not really "what's appropriate touching?", but rather, in what context is casual touching suitably welcome in daily life. Whether you're male or female, this is all I can come up with: a few gender non-specific situations whereby touching another person may be permissible.
Touching somebody is appropriate if you're likely to stop them being harmed. It could be as small as an impending bee sting or as big as moving somebody out of the way before a bus goes past. That one should be pretty simple to comprehend.
It can also be okay if you're trying to lower their embarrassment level – e.g. you find stray animal hairs on their shoulders – when you give verbal warning that you're helping them. Presentation of the offending extra material generally can quell anyone's concern over inappropriate touching, but by no means is it all right to reach for somebody's chest/butt/legs etc. to pull off rogue bits of cotton from their clothes.
Perhaps most importantly, touching can be appropriate when there is an established relationship and the appropriate level of friendship or romantic interest has been developed. It's too precarious to try and come up with a list of places/gestures on the body that are okay to touch based on different relationship qualifiers because every person/situation is unique.
Aside from actually asking, my only advice is to make eye contact with the person, ensure the body language is receptive (if in doubt, don't), move slowly so they can see exactly what you're doing, allow plenty of time to protest, and respect a verbal "no" or non-verbal negative cue, flinch or other rebuttal.
That's about it. I can think of no other ways where touching is allowable. More important, I think, is to offer tangible ways to tackle touching when you're NOT comfortable with it – no matter the intent of the offeror.
Ashley Judd has been the most helpful role model in how to understand inappropriate touching, as she frequently provides the public with actual responses that work in real life to counter any situation.
My favourite of Judd's advice is a simple hand gesture: arm extended, palm out, fingers apart (something akin to what a police officer would do to yield cars to a stop at an intersection with faulty traffic lights). Judd notes that this doesn't have to come with a verbal no – the hand movement on its own is universally understood and non-threatening. If "the hand" goes unacknowledged by someone and they continue, they are blatantly disrespecting you – and you should remove yourself from the situation as soon as physically possible.
Understandably, it feels like we've entered a field of land mines with all this talk about sexual misconduct, yet there's very little practical advice out there. While the onus is never on a victim to stop any kind of inappropriate touching – it's on the perpetrator to change their behaviour in the first place – it's important to know that any kind of touching is wrong if it feels wrong to you.
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