You may have noticed that the other three result types can all be expressed in terms of objects moving into the target space (Material Effects,) structural elements moving in or around the target space (Structural Effects,) or victims or their possessions being moved through or out of the target space (Motion Effects.) But some physical changes do not involve spatial changes at all; they involve changes of state, such as light, temperature, humidity, air pressure, noise level, odor, magnetic properties, or other sensory qualities named as trap detection methods.
Audible State Effects create noise, either as an alarm, as a distraction (to cover the sound of monster movements, for example,) or as a trick; extremely loud noises may even act as a weapon, stunning or causing damage in those who hear it.
Visible State Effects would include light or color changes, such as a bright flash to blind victims or a projection of a shadow to trick them. A room can also be lit to begin with, perhaps luring adventurers into dousing their torches, only to suddenly kill the lights right before they enter a room full of pits, or before releasing a monster.
Odorous State Effects can be odors designed to trick victims into believing a dangerous monster is nearby, scents to mask a real danger, or odors that have a side effect, such as sneezing or gagging.
Warmth State Effects or temperature effects involve increasing or decreasing the temperature of an area to make it unbearable or even cause damage. This could be wide area (an entire room reduced to frigid levels, to cause hypothermia,) or it could be a very focused target (heating a metal door handle to make it impossible to open without causing damage.)
Electrical Effects work in much the same way. A subcategory, Magnetic State Effects, can be used to slow or halt movement of victims wearing metal armor.
Tactile or Gustatory State Effects probably won't be stand-alone effects, but will be included with another effect, such as painful light or noise.
All of these are physical state effects and generally based on some kind of Material Effect. For example, temperature effects are usually accomplished through superheated air or boiling water, and gagging odors are usually produced with odorous material. If the material is introduced directly into the area (pouring boiling water on victims, for example,) State Effect traps are detected in the same way as Material Effect traps. However, many state effects involve the indirect application of materials, such as pumping wretch-inducing sewage into pipe beneath a floor and only allowing the stench to escape. These indirect trap effects are often more difficult to detect, since the material that produces the state does not have to enter the room.
The subtype of state effect is of course detectable by the named sense. A trap that produces a blinding flash involves some device that is visible, so it should be detectable by sight (Vis/S.) Some traps that have been used previously, but are not currently active, may leave lingering signs of their effects: the wretch-inducing sewage may leave a faint odor after it is pumped out of the area.