Taking 10 on perception checks to notice an ambush

Lets say the party is exploring a dungeon. The DM decides to spring an ambush on the party. Can they take 10 on the perception check to notice the ambush?

Lets say the party is exploring a dungeon. The DM decides to spring an ambush on the party. Can they take 10 on the perception check to notice the ambush?

Up to the GM, that said, taking 10 is unlikely to catch a good Ambush.

hahaha! that is so funny.

So what you are saying is, they are actively and noticeable searching FOR an ambush.

I would say that would be really obvious to the people who are laying in wait in the ambush, so sure they could do it, but who is to say that the ambush doesnt get sprung BEFORE they are done taking the 10?

basically, IF the ambush is about to get noticed, they would spring it, so the answer is a default, no.

I would rule potential danger as a stressful situation, though I guess the whole point is that the characters aren't stressed BEFORE it happens... I would still call it a combat-related situation!

I could see ruling wither way, but like Dragnmoon said... unless the "ambush" was meant to have little chance of surprising the party anyway, taking 10 probably wouldn't cut it, even if the GM says the characters can.

So what you are saying is, they are actively and noticeable searching FOR an ambush.

I would say that would be really obvious to the people who are laying in wait in the ambush, so sure they could do it, but who is to say that the ambush doesnt get sprung BEFORE they are done taking the 10?

I think you´re mixing up Take 10 and Take 20.

AFAIK, Taking 10 is totally legit by the rules...

I used to roll secretly for each PC at the beginning and after any major events in dungeons. I'd keep that roll for perception checks just to keep the game rolling. No fair to let the PC's know how well they are perceiving things.

Taking 10: When your character is not in immediate danger or distracted, you may choose to take 10. Instead of rolling 1d20 for the skill check, calculate your result as if you had rolled a 10. For many routine tasks, taking 10 makes them automatically successful. Distractions or threats (such as combat) make it impossible for a character to take 10. In most cases, taking 10 is purely a safety measure—you know (or expect) that an average roll will succeed but fear that a poor roll might fail, so you elect to settle for the average roll (a 10). Taking 10 is especially useful in situations where a particularly high roll wouldn't help.

I would call an ambush, even if it's happened in a few seconds a "danger".

Except the bolded parts you quote refer to being IN combat.
Obviously, a Perception check BEFORE combat (or threats of) has started is not aware of any distractions or threats. Which is crucially the point... Taking 10 doesn´t take any longer, and since there is no stressful situation impeding on your Perception BEFORE the check is made, I just don´t see why you can´t Take 10 here.

Of course, people can play however they prefer, no big deal...

i think taking 10 is a good way to represent the guy whos actively paying attentiona s the group walks a oposed to somone staring at their feat after the hours long hike.

Really unlesss you have eagle eyes mceagleson for a passive perciever it should only spot a poor Ambush.

I had been undr the impresson lots of groups used take 10 as a passive perceptionf or these sorts of things.

Except the bolded parts you quote refer to being IN combat.

Obviously, a Perception check BEFORE combat (or threats of) has started is not aware of any distractions or threats. Which is crucially the point... Taking 10 doesn´t take any longer, and since there is no stressful situation impeding on your Perception BEFORE the check is made, I just don´t see why you can´t Take 10 here.

Of course, people can play however they prefer, no big deal...

Expect for the bolded part at the beginning.

When your character is not in immediate danger or distracted

I would consider an ambush to be immediate danger, even if the party doesn't know it.

Of course it might depend on the ambush, if the party has set up camp and the enemy is ambushing the camp I might let the party take 10, they have set up sentries, they are patrolling and basically control the environment.

Walking down the dungeon its the other way round and I wouldn't allow the take 10 since they don't control the environment, the torch may flicker at the wrong time, they are distracted by the dripping etc.

Well, I suppose it´s different if you want to read ´immediate danger or distracted´ as to completly separate things, vs. as manifestations of the same concept. I read them as manifestations of the same concept, namely the dangerous/disturbing/distracting situation impeding on the character´s capacities to use their skills. In this case, when making the check there is nothing in the character´s environs or perception which is impeding on their use of skills.

I think it´s disengenuous to only focus on one of those bolded sentences, when it´s pretty clear that it is just repeating the same concept for emphasis. I mean, it also would then hinge completely on the definition of ´immediate danger´, which is undefined. I mean, imagine you are walking down a long hall way where enemies have an ambush prepared which they will implement in 3 rounds, so while you are walking down the hallway for 3 rounds you can´t take 10 on Performance checks on the flute you´re playing? Because, outside of your perception and without the capacity to influence the outcome of your check, you are ´in immediate danger´?

Anyways, that´s my 2c, play how you like...

Lets say the party is exploring a dungeon. The DM decides to spring an ambush on the party. Can they take 10 on the perception check to notice the ambush?

No.

The party is in danger.

The party cannot take their time and leisurely look for an ambush.

Depending on the ambush, the party, the DM, and the pace of the characters, the DM might FORCE the party to take 10, rather than allowing them to roll (and thus allowing them the chance to roll high).

This isn't RAW, but it would probably make ambushes more often successful.

Depending on the ambush, the party, the DM, and the pace of the characters, the DM might FORCE the party to take 10, rather than allowing them to roll (and thus allowing them the chance to roll high).

This isn't RAW, but it would probably make ambushes more often successful.

Absolute, unacceptable, inexcusable DM cheese. It's outright Limburger.

The party cannot take their time and leisurely look for an ambush.

This seems based on the same premise as Pendagast´s comment.

+1 to your Limburger comment...
That´s basically reducing variability just to achieve an intended outcome.
Why not force Take 10 attack rolls when you know that won´t hit the NPC AC?
Why not just say ´you lose, regardless of what the numbers are´? Same result... same cheese.

I mean, to a GM with low skills, that may seem their only option, and maybe that helps them tell the story best within their skills. But they SHOULDN´T have to rely on such ham-handed methods. At the least, that is seriously trust-breaking for players who expect the GM to play by the rules.

Absolute, unacceptable, inexcusable DM cheese. It's outright Limburger.

Only if you don't tell them they stand a better chance of detecting ambushes by not running through the dungeon recklessly. So long as it's declared beforehand, and the players understand, I don't see anything wrong with such a rule.

Now if it's decided that the party ALWAYS takes 10 on perception vs. ambushes, then I'd agree with you. But the way I meant to present it is more "a party that runs through the dungeon only gets to take 10, whereas a party that is being at least a little cautious rolls instead".

The idea being that you wouldn't declare your character as running recklessly through the dungeon unless you've got a very good reason to do so.

If you are having the enemy take 10 then it might be ok but letting the enemy roll and not the players is not fair to the players. Rolling the dice lets the players think that their decisions can actually effect the world. Making them take 10 is not a DM choice it's up to the player to decide if they want to or not. You are also always making perception checks while most of the time it doesn't matter. This is why people get distracted sometimes and roll 1's and sometimes they are really focusing and gedt 20's. Leave it to the dice and I think your players will be happier. If you make arbitrary decisions for players then they will resent you later for it. If they die because they rolled poorly then they have nothing to blame cept the dice and their own decision making.

I don't know, if the player characters decided to take a quick sprint through the dungeon I do not think I would force (or even allow) them to take 10 on perception checks... I would make them roll while assigning a hefty penalty to the check.

Well, I suppose it´s different if you want to read ´immediate danger or distracted´ as to completly separate things, vs. as manifestations of the same concept.

Well, that big 'O "or" in there makes them separate things to my eyes.

I think it´s disengenuous to only focus on one of those bolded sentences, when it´s pretty clear that it is just repeating the same concept for emphasis. I mean, it also would then hinge completely on the definition of ´immediate danger´, which is undefined.

I call strawman on that argument, specially when in your original post you picked out the "combat" bolded sentence.

I mean, imagine you are walking down a long hall way where enemies have an ambush prepared which they will implement in 3 rounds, so while you are walking down the hallway for 3 rounds you can´t take 10 on Performance checks on the flute you´re playing? Because, outside of your perception and without the capacity to influence the outcome of your check, you are ´in immediate danger´?

Strawman two, does the performance have anything to do with the threat at hand? Why are you taking 10?

cwslyclgh has a good point, how much effort is the group putting into being alert for an ambush?

I just dislike the take 10 mechanic, I dont see why anyone would be able to achieve an average result all the time. rolling 1d10+5 I can imagine, take 10 I use just as a mechanic to speed up play.

BY RAW I do not see a reason not to be able to take 10, they are not in combat or danger they are aware of, they are just being methodically careful. Unless they are busy doing something else I'd allow them to take 10.

I just dislike the take 10 mechanic, I dont see why anyone would be able to achieve an average result all the time. rolling 1d10+5 I can imagine, take 10 I use just as a mechanic to speed up play.

BY RAW I do not see a reason not to be able to take 10, they are not in combat or danger they are aware of, they are just being methodically careful. Unless they are busy doing something else I'd allow them to take 10.

Raw does not say you have to be in "danger you are aware of". Raw says you are in danger. When trying to spot an ambush you are, by definition, in danger. You cannot simply add words to the sentence and insist on it being raw.

So if they are not checking for traps because they are in a corridore, and the whole corridore is a trap, can a GM rule that the rogue is taking 10?
Otherwise you are asking them to roll perception and they run screaming back the way they came. :)

Taking 10 seems to me to be an acceptable rules interpretation. I would read "immediate danger" the same way that Quandary does. The party isn't distracted or aware of their danger so they can take 10 on any skill roll, including spotting an ambush.

However, I don't see how this is any different than any other skill check, I don't believe it is RAW to be able to take ten perpetually on any skill check. You still have to say "I'm taking 10 on a perception check to detect an ambush." So if you happen to take ten at a time when the ambush is detectable AND the 10 succeeds, then, yes, I would rule that it works. But the odds are not in your favor.

As a DM what I usually do is secretly roll perception checks individually for characters using modifiers that I think are appropriate for the situation. That way the party gets a chance to detect the ambush. The sorts of things I use to modify the DC of the check are things like the following:

1. Has the party role played a reasonable sense of danger awareness? Do they have a marching order for example?
2. How long have they been marching without encountering anything?
3. Is the party role playing inter-party interaction at the time? Joking, teasing, fiddling with equipment, etc?

Based on those and other things (like the weather, the location of the sun, the direction of the wind...) I might modify the base DC by +4 to -4 and then make their rolls.

What if the ambush is not for them? Are they still in danger if the ambushers have no intention of breaking cover until after the party is long gone?
How does it require any more or less concentration to notice a person hiding depending on that person's motivations?

RAW also says "immediate danger" not "danger a few seconds from now". So RAW, you can take 10s up until immediately before the ambush springs.

I thought immediate danger meant someone is trying to cut your face off with an axe, not there's a slippery rock you're about to slip on and break your leg. Cause to say I can't take ten because I might be about to step on a rock seems odd.

This is one of the simplifications I think 4E handles nicely.

If the party's specifically looking for something (ie, I scout ahead and look out for potential ambushes) then they get a roll.

If not they use passive perception, which is equivalent to taking 10 on the check.

GM cheese has nothing to do with it, it's a way of keeping things moving.

If I want the ambush to succeed I can do a dozen other things to make it succeed, from situational bonuses (the bad guys have been using this spot for months and know exactly where to hide) to one-time use items (potions of invisibility/elixir of stealth and a familiar/animal companion spotter) to just giving them higher stealth checks. Since a Nat 20 doesn't auto succeed on a skill check, all I need is a stealth equivalent to the highest perception +1.

Now THAT's a bit cheesy, but now we're onto a whole other discussion

At first, I was going to say "no way, that's a reactionary check!" Then I remembered that, as GM, I have people on alert (such as city patrol, guards, bodyguard, etc.) take 10 on such checks all the time.

As such, I think it is doable provided it is declared in advance. Kind of like the opposite oh how 4E does it.

Raw does not say you have to be in "danger you are aware of". Raw says you are in danger. When trying to spot an ambush you are, by definition, in danger.

Ok, I play my flute, taking 10, all day, every day. As soon as I'm asked to roll, I know I'm in danger and can take actions appropriately.

On the other hand, not knowing that I'm in 'immanent'danger, I continue to take 10 till the danger presents itself because the stress that this danger poses doesn't take effect till I know of it.

Yes, I'm well into RAI territory here, but as I see it the take 10 mechanic is twofold. The first, speed up play. The second, to simulate that people can perform routine functions in a steadfast manner, rather than the 19 point spread represented by a d20 roll.

To answer the OP I'd allow my players to take 10 (or as 4e calls it a 'passive' score) as long as they weren't currently being presented with danger.

The players aren't in danger, so taking 10 is appropriate and valid by RAW. I think it is meta-gaming on the GM's part if they insist that the players make perception checks as they will soon be in danger.

Unless players indicate that they are taking extra precautions, I go with them taking 10 on perception checks. This works for everything - noticing ambushes, tracks, hidden items, etc...

I don't like telling the players "OK, make a perception check" out of the blue, as it tells them something is about to happen, or could happen. I don't like to break the immersion of the players with extra rolls.

I also don't want to spend the night with the players rolling perception check for every 5' square they walk thru.

Lets say the party is exploring a dungeon. The DM decides to spring an ambush on the party. Can they take 10 on the perception check to notice the ambush?

Sure.

Just like you can take 10 on a climb check over a pit of liquid hot magma. There's danger around, but you're not in the thick of it yet.

Someone falls in and you're racing to climb down to help pull them out of the magma.. then no.

Likewise for spotting the ambush.

I normally have many NPCs & PCs alike take 10 on such checks when it seems reasonable.

-James

I'd say it's fair enough to take 10 in that case. After all, the PCs shouldn't actually know it's an ambush until they actually get ambushed, so there's no basis that they're in danger. Acting otherwise would require the GM to be a real cheeseball, IMHO.

Question wrote:

Lets say the party is exploring a dungeon. The DM decides to spring an ambush on the party. Can they take 10 on the perception check to notice the ambush?

Sure.

Just like you can take 10 on a climb check over a pit of liquid hot magma. There's danger around, but you're not in the thick of it yet.

Someone falls in and you're racing to climb down to help pull them out of the magma.. then no.

Though I agree with you 100%, I remember a time not too long ago when there was a 100+ post thread won these forums where people actually debated whether or not you could take 10 to jump over a 5-ft. wide, 100-ft. deep chasm because of the "danger" involved.

Such is the internet, I guess.

I still don't see "take 10" as an "always on" feature for any skill. It's a way to speed up common skill checks, not an aura of perception that the player can depend upon.

My problem with the idea of the characters "taking 10" on all perception checks to spot an ambush is that this forces the DM to metagame the situation. Based on the DC the ambush is either automatically spotted (in which case it's hardly an ambush) or it's automatically missed (in which case the party never really had a chance to detect it in the first place).

So in the interest of playing out the scenario I would never run an ambush detection under a "take 10" perception check unless the players happened to be right at the ambush and happened to say "We're taking 10 on our perception checks". Otherwise I want the characters to have a chance of either spotting or not spotting the ambush instead of having the outcome predetermined by the ambush DC.

But that's just me. That's one of the things I dislike about 4e, by the way, the whole passive perception thing that is supposed to "speed up" the game but just ends up with DMs making the decision on whether something is detectable or not simply based on the passive perception check alone. That just doesn't feel right to me.

Lets say the party is exploring a dungeon. The DM decides to spring an ambush on the party. Can they take 10 on the perception check to notice the ambush?

Players can take 10 on perception but I don't see how that would help them find an ambush.

It is important to note that perception won't tell them everything. For instance hearing a character standing behind a door being quiet has to be like a 25-30 check or even higher if they have a good stealth check. You hear someone behind the does does not mean:

"you hear an ambush of 30 katana wielding ninjas"

Karlgamer makes a good point.

What's more, there's nothing preventing the ambushers from taking 10s on their stealth checks if they were being careful about their setup. Heck, a good ambush might be allowed to take 20 if they've had ample time to set up the area.

I think this would keep ambushes plausible (in that they actually work sometimes, even with normal enemies) and reduces the amount of metagame cheese on the GMs part.

They have the option of telling the GM that they move at half speed because they are actively looking for an ambush or trap. That's not a good idea in town because such things are usually on a timetable.

An ambush is meant to surprise the players. If the players actively do some scouting and make there checks(even taking 20) they should get the benefit. This doesn't ruin an ambush. It just gives the players the surprise round.

Unless the players wait for any buffs to end or set up an ambush of there own.

Players should be rewarded for being cautious and clever.

This is why my DM has a list of all of our Perception checks. If he needs to he just rolls the opposed Stealth and Perception checks behind the screen. We have the option of course to say "Hey, I'm feeling a little paranoid right now, let's slow down and check this corridor carefully (self rolling, perhaps even take-20)" or "I'm not sure I trust the dice right now, I'm just gonna take-10 for the next little while, ok?" If we don't declare that, he makes the rolls and lets us know what happens. No metagaming, nice and clean.

I still don't see "take 10" as an "always on" feature for any skill. It's a way to speed up common skill checks, not an aura of perception that the player can depend upon.

Except that people do have auras of perception. It's called your eyes and ears. We notice things going on around us without active effort all the time. Let's take the whole "actively looking" aspect out of the equation.

Let us suppose that you are sleeping. Now if you are approached by someone trying to sneak up and kill you, you are entitled to a perception check. While you are sleeping, is it reasonable for you to possibly make a 20? Is it reasonable for someone to randomly be as aware while asleep as when they take 10 for 8 hours of guard duty? To me if you're actively looking you can make a roll, but it is unreasonable to say that someone can be actively looking for something like an ambush for 8 hours.

I still don't see "take 10" as an "always on" feature for any skill.

Why not in the case of perception? I regularly use the skill while doing... just about everything. My eyes are open most of the time, and my ears alert me to strange noises even as I sleep (or the alarm).

I find it especially useful for not getting run over while crossing the street, and not getting mugged (spotting ambushes and the like) whenever I have to go to Phoenix.

My problem with the idea of the characters "taking 10" on all perception checks to spot an ambush is that this forces the DM to metagame the situation.

Not any more than you have to metagame that there will be an ambush. It works much like if they weren't taking 10 except that once conditions are established you know the DCs your ambushers are (all) trying to exceed, instead of both sides rolling.

Otherwise I want the characters to have a chance of either spotting or not spotting the ambush instead of having the outcome predetermined by the ambush DC.

Even if the enemy doesn't beat the highest perception, there's still a surprise round against any who's perception they did beat (as per reactive perception)

I see where you're coming from, but the idea of a passive score doesn't prevent people from saying 'I look around' and getting a perception check that way. Back in 3.5 I spent a feat just so I could have a 'passive' spot and listen (told my DM I was making spot and listen checks every round as free actions per the feat).

They have the option of telling the GM that they move at half speed because they are actively looking for an ambush or trap. That's not a good idea in town because such things are usually on a timetable.

It also makes them look awfully suspicious being so suspicious.

brassbaboon wrote:

I still don't see "take 10" as an "always on" feature for any skill. It's a way to speed up common skill checks, not an aura of perception that the player can depend upon.

Except that people do have auras of perception. It's called your eyes and ears. We notice things going on around us without active effort all the time. Let's take the whole "actively looking" aspect out of the equation.

Let us suppose that you are sleeping. Now if you are approached by someone trying to sneak up and kill you, you are entitled to a perception check. While you are sleeping, is it reasonable for you to possibly make a 20? Is it reasonable for someone to randomly be as aware while asleep as when they take 10 for 8 hours of guard duty? To me if you're actively looking you can make a roll, but it is unreasonable to say that someone can be actively looking for something like an ambush for 8 hours.

No, your eyes and ears are not "auras of perception." Neither do you "notice things going on around you without active effort all the time." That's why the internet is full of videos of people walking into manholes or walking into moving traffic. Because your perception is NOT "always on." You have to be actively looking around. If you are driving you have to look in your mirrors, check beside you and ACTIVELY monitor the status of all cars around you. If you don't, you're just an accident waiting to happen.

Similarly, when you are hiking for mile after mile in the forest, or trudging mile after miserable mile in a dark, dirty hole in the ground, you have to make an ACTIVE effort to look around, because your normal inclination is to watch your feet as you trudge.

However, it is quite possible that one of the party IS paying attention and looking around at any given moment. That's why I always roll to give them that chance.

I gave my party the option last session.

They could either assume they were staying fairly vigilant, and take a 10 - representing someone generally paying attention to their environment, OR they could choose to roll, but they could just as easily have a scout who was wathing ants crawling on a rock with a 1 as they walk into a killzone.

Frankly I see a good case for everyone to take 10 and notionally represent being aware, vs the active check that might more resemble the "SHH everyone stop a second, I think I heard something" active roll.

I gave my party the option last session.

They could either assume they were staying fairly vigilant, and take a 10 - representing someone generally paying attention to their environment, OR they could choose to roll, but they could just as easily have a scout who was wathing ants crawling on a rock with a 1 as they walk into a killzone.

Frankly I see a good case for everyone to take 10 and notionally represent being aware, vs the active check that might more resemble the "SHH everyone stop a second, I think I heard something" active roll.

So, does your party realize that they have agreed to walk blindly into any ambush you create with a DC one higher than their highest take 10 roll?

And if so, they are OK with this?

My players would have a frickin COW.

Alternatively are YOU OK with the fact that if you now make your ambushes detectable by the party that they will never be ambushed? As a DM I'd never accept that. I'd just do away with ambushing altogether, because there's no such THING as an ambush anymore.

Alternatively are YOU OK with the fact that if you now make your ambushes detectable by the party that they will never be ambushed? As a DM I'd never accept that. I'd just do away with ambushing altogether, because there's no such THING as an ambush anymore.

An attempted ambush is still an ambush. What's wrong with letting people who invested in Perception be rewarded for it?

People who invest in Perception have ranks and bonuses. When they pick something out, they are rewarded for it.

You can't let them take 10, becuase the dichotomy is a)they aren't in danger unless the ambush is sprung, or b) you're letting them take 10 in a dangerous circumstance.

A) means they'll jsut say "we are always taking ten looking for ambushes, which is poor roleplaying, makes your job harder, makes adventuring easier, and cheapens the vigilance required in actively sniffing out ambushes. There's no tactical genius in letting your party fail to recognize a great bottle-neck, and then have them say "but we aren't flat-footed because last year we told you we always take 10 on Perception checks".

B) is straight up against the rules and makes little sense anyway. Taking 10 on Perception checks to search someone's house makes sense. Taking ten to listen in case someone is shuffling their feet behind that escarpement does not. Either you heard them when it happened or you did not.

And who wants a party that feels cheated when they get ambush them? I say ambush them every week until dead!

EDIT: One idea I do like from 4e (and maybe the only one) is passive perception. Effectively, give them a ten for things they might notice when not telling you they are looking for something in particular. Of course, that runs you into the problem of designing ambushes jsut over their passive scores, but then if someone gets suspicious (aka recognizes that bottleneck up ahead), them you can reward their wariness with an opposed roll. Best solution I think.

BigNorseWolf wrote:

Raw does not say you have to be in "danger you are aware of". Raw says you are in danger. When trying to spot an ambush you are, by definition, in danger.

Ok, I play my flute, taking 10, all day, every day. As soon as I'm asked to roll, I know I'm in danger and can take actions appropriately.

On the other hand, not knowing that I'm in 'immanent'danger, I continue to take 10 till the danger presents itself because the stress that this danger poses doesn't take effect till I know of it.

Yes, I'm well into RAI territory here, but as I see it the take 10 mechanic is twofold. The first, speed up play. The second, to simulate that people can perform routine functions in a steadfast manner, rather than the 19 point spread represented by a d20 roll.

To answer the OP I'd allow my players to take 10 (or as 4e calls it a 'passive' score) as long as they weren't currently being presented with danger.

Thats not RAI either. The take 10 mechanic is intended to get non important non combat stuff out of the way without a lot of rolling so you don't need to make use rope checks to tie your shoes or craft armor smithing to repair a few rends in your chainmail. It is NOT meant for fore ordain who gets to act in the surprise round.

Okay, so if your going to set up an ambush in a room you would:

Turn over a table and have your range character and wizards hide behind that. Set up your tanks by the door and the wizard and cleric buff all the players (assuming they have a wizard and cleric.) The bard keeps clearing this throat preparing to sing(I don't know.) you get the idea.

If the players detect that someone is behind the door: they haven't detected that they'res and ambush just that theres someone behind the door.

If they roll a 40 on there perception check you could tell them "you think theres over three people in the room and there trying to be quiet"

Never tell your players "There are 5 people in the room: one cleric, one wizard, one fighter, one rogue and a druid" unless they roll like a 60 on there perception check.

checking for an ambush is always going to be over 25. unless the ambushies are idiots in which case: Yes your players should be able to notice them.

How suspecting an ambush in a room help is up the the players. Most of the time it just means that the players get to act in the first round of combat.(You should always give your players a perception check to act in the surprise round anyway)

Your casters need to get a chance to buff there companions before combat sometimes.

Plus. If your players are kick in the door players they're always prepared for an ambush anyway.

No, your eyes and ears are not "auras of perception." Neither do you "notice things going on around you without active effort all the time." That's why the internet is full of videos of people walking into manholes or walking into moving traffic. Because your perception is NOT "always on." You have to be actively looking around. If you are driving you have to look in your mirrors, check beside you and ACTIVELY monitor the status of all cars around you. If you don't, you're just an accident waiting to happen.

How many times have you just spotted something out of the corner of your eye? How many times have you casually overheard people talking about you (or something you're interested in)? We do it all the time.

Regarding the youtube videos: distraction penalties, circumstance penalties, and a neg wisdom eat away a 10 to failure of common tasks.

While driving, we are forced to rely on only one of our senses. We use our sense of hearing typically to estimate things outside our line of sight, meanwhile our ability to hear other cars is nullified by the fact that we are in an enclosed object. As a matter of fact, I don't believe there are many restrictions on deaf people driving. However, deaf people would have a significant disadvantage when it comes to detecting ambushes, invisible people, etc. Even if you put hearing aside, I know that you don't constantly look at your mirrors when you're driving straight down a highway. You look at mirrors when particular events come up such as changing lanes or making turns. It is akin to being more careful of ambushes when something significant changes in the terrain. I'd grant a roll if the party was already explicitly wary of ambushes and they just entered a narrow cavern but not when they continue walking through a jungle. That being said if the trip is sufficiently short (15 min. starts to push it) and they're pre-emptively wary, I'll let them qualify as constantly vigilant; however, if it's a 5 hour ride, it's like driving in west Texas, you're no longer vigilant within about half an hour.