Consciousness derives from Com (with) + Scio (knowledge). It is a much debated and controversial topic and an unresolved mystery. One simple test of consciousness (self-awareness) is the ability of a being to recognize its image in a mirror and act appropriately. A lion in front of a mirror fails to recognize its image in a mirror and treats it like another hostile lion and attacks it. Even monkeys fail and only the apes (chimpanzees, gorillas) pass the test and that too slower than a human child. A more complex test is to anesthetize a great ape, put some removable non-irritant paint on the forehead and when it wakes up, confront it with a mirror and see if it attempts to rub off the paint on its own forehead (not on the mirror image) when faced with a mirror. A success on the test shows consciousness extending to self-awareness.
I am going to apply the same criteria to subatomic particles and give details of physics experiments and analogies which are from Brian Greene's excellent book 'The Fabric Of The Cosmos'. If we take a source of light like a laser beam or any ordinary light and place a solid obstacle with a single slit in front of it and a screen behind the obstacle, we will see a single slit image on the screen. This is like firing a machine gun in front of the slit. Those bullets that are aligned with the slit will pass through and hit the screen in the shape of the slit. If we were to cut a second slit close to and parallel to the first slit in the obstacle and fire the gun, the bullets will strike along the shape of the two slits on the screen and will have a two slit distribution. If we do the same thing with the laser, what we see instead is an interference pattern (alternate light and dark bands) covering the area between and slightly beyond the two slits. This was an early experiment that proved that light travels in the form of a wave. Similar configurations are seen in a body of water when two propagating waves collide and form a series of single waves and troughs where the two waves are in phase and out of phase respectively. This is the science behind the Bose earphones available in the market today to block other noises.
The problem is that when Davisson and Gerner fired a beam of electrons through a double slit they got the same interference pattern. Electrons are supposed to be particles and yet they can behave like waves too. In another experiment with lasers, others turned down the firing intensity of a laser beam till it was emitting single photons at measurable time intervals and yet the interference pattern was seen. This proves that subatomic particles like photons, electrons etc. can behave either like particles or waves. It gets even worse. Many of you must have seen a wall consisting of a half silvered mirror. It is used in focus groups and by police for a party or person to observe the focus group or identify a crime perpetrator by a victim from a line-up. In physics such a contraption is called a beam splitter. It allows half the photons to pass through and reflects the other half in a random fashion Any single photon can either pass through or be reflected. The photon beam is shone and the reflected photons hit another mirror and are then redirected in such a way as to meet the photons that passed through and then via the slits to the screen. Once again we see an interference pattern.
The light or laser is dimmed so much that it emits only single photons at an interval of few seconds. Any single photon can either pass through or be reflected. One would expect than the two light beams would behave like the two streams of machine gun bullets. If we now put a photon detector in front of the beam splitter mirror which will detect every photon that doesn't pass through it and is reflected and carry out the experiment, the image on the screen changes from the interference pattern to two slits as in the machine gun experiment as the photons now choose to behave like particles and not waves. It has been made complicated by placing a detector in front of one or both slits (further down the path from the beam splitter). Even if one or both detectors are turned on only after the photon has traveled beyond the beam splitter, the interference pattern is replaced by two slit images. The photons behave like particles and seem to know in advance that the experimenter would turn on the detectors. If you can know that they behaved like particles they will do so. If that knowledge is hidden they will behave as waves. If they know that you know, they alter their behavior in a predictably consistent fashion.
Subatomic particles have a property called spin (which maybe clockwise or anti-clockwise). One can make the experiment more complex by placing a tagging device in front of the slit that alters the spin of a photon to a specific direction. The screen can be devised such that the impacts of photons with a specified spin can be identified. If this is done then the image seen is two slits and not the interference pattern. If tagging devices are placed in front of each slit, such that the photons passing through either slit have identical spins and cannot be distinguished by their impact on the screen, the interference pattern reappears. If spin modifying devices are placed behind the slit but in front of the screen so that both streams of photons have the same spins and spin direction ceases to be an identifying marker, once again we get the interference pattern. For even more complicated and bizarre experiments and results using down converters splitting photons and their more complicated paths and the use of detectors leading either to a double slit or interference pattern image depending on switching detectors off and on you need to read the book. The conclusion is that the subatomic particle switches from a particle to wave form by having the ability to know how the experimenter is going to modify the experiment or is able to go back in time and modify its behavior to suit the experimenter. Surely this denotes a form of conscious self-awareness in the particle about itself and its environment.