When using the Detect Thoughts spell, is the target aware that you're probing its mind when you're not doing a deep probe?

Question

I'm considering experimenting with the Bard: College of Satire from Unearthed Arcana: Kits of Old, but whether or not I can be discreet with the Detect Thoughts spell is keeping me on the fence.

In the spell description on page 233 of the PHB, the 2nd paragraph talks about what you can read from focusing on a target. It explains what you get by default, then explains how you can do a deep probe, what you get on success and what you get on failure. After that comes the text (part of the same paragraph but a separate sentence):

Either way, the target knows that you are probing into its mind, [...]

Does that refer to the deep probe (either outcome), or does it apply to the spell in either use case?

Answer 1

The creature is only aware when you probe deeper, not when you learn surface thoughts

Detect Thoughts says:

You initially learn the surface thoughts of the creature—what is most on its mind in that moment. As an action, you can either shift your attention to another creature’s thoughts or attempt to probe deeper into the same creature’s mind. If you probe deeper, the target must make a Wisdom saving throw. If it fails, you gain insight into its reasoning (if any), its emotional state, and something that looms large in its mind (such as something it worries over, loves, or hates). If it succeeds, the spell ends. Either way, the target knows that you are probing into its mind ...

The "either way" is specifically about the "probe" and its position in the paragraph means that the either/or alternative is the passing or failing of the saving throw not the shallow or deep probe.

Answer 2

The creature is only aware when you probe deeper

Found a section of the PHB that seems to specifically addresses this. On page 204 in the spellcasting section 2nd paragraph of the targets subsection

Unless a spell has a perceptible effect, a creature might not know it was targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature's thoughts, typically goes unnoticed, unless a spell says otherwise.

Answer 3

The creature is always aware.

Let's get the whole paragraph of that part of the Detect Thoughts spell up to analyze.

"You initially learn the surface thoughts of the creature—what is most on its mind in that moment. As an action, you can either shift your attention to another creature’s thoughts or attempt to probe deeper into the same creature’s mind. If you probe deeper, the target must make a Wisdom saving throw. If it fails, you gain insight into its reasoning (if any), its emotional state, and something that looms large in its mind (such as something it worries over, loves, or hates). If it succeeds, the spell ends. Either way, the target knows that you are probing into its mind, and unless you shift your attention to another creature’s thoughts, the creature can use its action on its turn to make an Intelligence check contested by your Intelligence check; if it succeeds, the spell ends."

Due to the nature of the final sentence in which the "Either way" is, the creature will be aware it is being probed regardless. The "either way" is in reference to the option to learn surface thoughts, or deeper probing.

There would not be a second chance to end the spell "either way" the creature rolled. If the creature succeeded the Wisdom save, the spell would be over. This sentence would not have any use after that point. The spell either ends or does not. So the last sentence can't refer to the previous one in that regard. The only logical conclusion therein can be that it is referring to either surface reading and deep thought probing.

This means the creature is always aware that it is having its mind probed somehow. No matter how shallow.

Let's break this down further. There are several outcomes for this spell to have on a single target by the reasoning I've described:

• You view the target's surface feelings. It is aware of your actions. It may make a contested Intelligence roll to end the spell.

• You probe deeper into its thoughts. It makes a Wisdom saving throw. On a failure, you gain more knowledge of the target as described. The target is aware of your actions, and can make a contested Intelligence ability check to end the spell.

• You probe deeper into its thoughts. It makes a Wisdom saving throw. On a success, the spell ends. The target is aware of your actions.

Now, in the other interpretation of this spell, the possibilities are as listed:

• You view the target's surface thoughts.

• You probe deeper. It makes a Wisdom saving throw. On a failure, you gain more knowledge of the target as described. The target is aware of your actions, and can make a contested Intelligence ability check to end the spell.

• You probe deeper. It makes a Wisdom saving throw. On a success, the spell ends. The target is aware of your actions, and can make a contested Intelligence ability check to end the spell. (What?)

Yeah that last one didn't make sense to me either. This is my reasoning for my answer. Break it down and see what you come up with. Now, if the sentence was this instead, the latter would make far more sense:

Either way, the target knows that you are probing into its mind. If you do not switch your attention to a new target's thoughts, the target may contest Intelligence ability checks with you to end the spell as an action on each of its turns.

If they were separate ideas they would not be in the same sentence.

Answer 4

Jeremy Crawford gives an "official" ruling in this September 2016 Sage Advice rules answers column, and it is reproduced in the Sage Advice Compendium.

It reads:

You’re aware that a spell is affecting you if it has a perceptible effect or if its text says you’re aware of it (see PH, 204, under “Targets”). [...] Certain spells are more subtle, yet you become aware of the spell at a time specified in the spell’s description. Charm person and detect thoughts are examples of such spells."

Answer 5

I'm reading it as "you probe surface thoughts" (unnoticed) "You can try to probe deeper" (provokes a save, at this point the target becomes aware of the spell affecting it) If target makes the save: spell continues to function, you do not glean more information about them. They can make an Int contest to end your spell. If target fails the save: you glean more information about them and the spell ends. Either way (pass or fail) the target is aware of the attempt.

In this reading, the caster can try again, or switch targets if the subject makes the save.

Answer 6

The creature is always aware

Separating each relevant sentence of the spell description into a separate line:

you can either shift your attention to another creature’s thoughts or attempt to probe deeper into the same creature’s mind.

If you probe deeper, the target must make a Wisdom saving throw. If it fails, [stuff happens]. If it succeeds, the spell ends.

Either way, the target knows that you are probing into its mind, and unless you shift your attention to another creature’s thoughts, the creature can use its action on its turn to make an Intelligence check contested by your Intelligence check; if it succeeds, the spell ends.

While @D.Sorrim's answer calling out the "spell ends" at the end of the two logic branches is sound logic, I base my supporting answer on the and unless part.

If something is saying "unless you shift" it must be referring to the choice to shift or not.

The preceding "and" links the preceding clause of the sentence to the same discussion. Which means the "Either way" must also be referring to the choice to shift.

Which means it can only be read as:

• "You can either
  • shift to another creature,
• or
  • attempt to probe deeper.
• If you probe deeper, target makes a Wis save.
  • If it fails, you get info.
  • If it succeeds, the spell ends.
• Either way,
  • the target knows you're probing, and
• unless you shift the creature can use its action for an Int check;
  • if it succeeds, the spell ends."

As code:

  if (player.shiftOrProbe == PROBE) {
    if (target.save(target.Wis)) {
       target.thoughts.print();
    } else {
       player.spell.end();
    }
  }
  target.addKnowledge("PLAYER IS SKEEVY BRAINSUCKER");
  if (!player.shiftOrProbe == SHIFT) {
    if (target.save(target.Int)) {
       player.spell.end();
    }
  }

On revisiting this, I do see one possible other way of reading it, though: it might be saying "if the player has an extra action, they can spend the action to probe deeply, then spend the extra action to shift to another target, before their target gets the chance on their own action to perform the contested int check. Either way, their first target will know they were probed." To me, this seems an unlikely alternate reading, but it is feasible given the ruling cited by Mujodoka.