Hey,
I am a noobie to these forums and I wanted to say hi first of all.
Second I have started playing a psyker in a dark heresy campaign and my DM insists that psyker powers are very visible and that when I use any, minor or major I have to make hand signs and vocalize the power. However I have not seen any mention of this in any of the rule-books, and so I want to know.
Do psykers just concentrate and focus on the power and have it manifest or do they have to do physical and vocal things to have it manifest?

Thanks for your time and sorry if this is a stupid question.

Welcome aboard, Nath0610 . What using psychic powers looks like is largely undefined and subject to interpretation, but I would suggest that your GM is thinking of D&D magic spells. Unless its a power that involves rays from fingertips or deafening screams, I rule that psyker powers are subtle enough to require an Awareness Test to spot the fact that the psyker is making any gesture at all (the "These are not the droids you're looking for..." hand-wave, for example). But, ultimately, the GM has the final word.

My own GM has agreed it depends on the power. If nothing is mentioned, then generally nothing is expected. Powers that target the mind, for example, have no visual cues. Honestly, it doesn't even mention that powers HAVE to be accompanied with gestures or vocalization-- unless you're doing an invocation test at least.

I suppose it's up to GM interpretation, but personally, I would consider it that if the rulebook doesn't state so, the power should be able to be done in a concealed manner-- unless of course you hit Psychic Phenomena. Depends on the power of course. Something like Inflict Pain, Precognition, or Telekinesis shouldn't be visible, in my opinion. Something like Bio Lightning or Firebolt absolutely would be.

Some powers specifically state that they can be used "covertly", in such a manner as the target remain unaware of anything happening at all.

I remember I asked the same question when I was a newbie GM, and the general feedback was that no, they aren't visible. (Unless you're throwing fireballs around, or shaping your own flesh, etc).

Using Invocation, though, involves gestures and words of some sort, and might be spotted.

Thanks all,
I tend to agree with all of what you were saying and so will try to convince my gm otherwise. (my biggest issue is the minor power suggestion as it feels kinda useless if it is seen as being used and it has very short range).
Thanks for the prompt responses.

Notice that sorcerous powers used by individuals who aren't naturally psychic explicitly have to use visible cues, hand gestures, words etc. This is because they accessing the warp through arcane means as a shortcut to overcoming their own lack of psychic ability. The implication is that normal psychic powers are essentially invisible.

As a compromise though I would probably say that using maximum number of dice to manifest the power, using the focus action and so forth probably represents making the power slightly more visible, however just using a single dice and relying on WP to manifest the power should probably be largely invisible.

I have always ruled that there is always a chance however that manifesting a psychic power can make people get a strange feeling of unease, deja vu or even nausea over and above psychic phenomena. Not enough to necessarily associate it with psychic power but enough to remind the players that psychic powers are not mundane tools and are always unnatural and potentially dangerous.

Some powers will be invisible if used the normal way, while others are blatant. This is one of the reasons why Psykers are branded, to warn everybody (and obviously to show they are sanctioned, for their own protection from the fearful reaction of others). Remember that psykers are a known entity in 40k, even if as "wyrds" and "witches", so if weird stuff starts happening around a bald person in long robes they are likely to work out what is happening, even if there are no bolts of magic lightning etc. A guy suddenly being torn into little pieces because he has been drilled with a Force Barrage is a clue something is up. Also, I think it is stated somewhere that targets of the telepathic powers are aware their minds are being violated regardless of whether there is any obvious visual clues, unless the power's description says otherwise.

Some of the more subtle powers (like the probability altering ones) might take longer for someone to realise something is up and the cause of it. There also might be other subtle clues, like the psyker looking like they are concentrating on on a target, even if they are not doing anything like pointing with fingers etc. Psykers also learn rituals to focus their powers, which is what Invocation represents, and these will usually involve obvious clues that are mentioned.

I have a pretty good GM, who can be strict on these matters. As far as psychic powers go, unless you are shooting lightning or floating, there is nothing going on. Sorcery is the school of warp manipulation that requires blood circles and chants. As far as invocation goes, it is up to the scrutiny of NPC to notice you making a chant under your breath or whispering a prayer. Normally, casting a psychic power is done all within the psyker's mind. Tell your GM to look at sorcery in Radical's Handbook, as it clearly states that what sets sorcery apart is the need for chanting and hand motions.