In the first season of SOA, IIRC, Kirito tells his friend that they can't feel pain in SOA. But later we see a lot of characters reacting like if they feel pain (screaming in pain, etc.) and also they enjoy and taste meals and foods. So, how is this possible?
Does people playing Sword Art Online feel something or not?
The Nerve Gear can theoretically simulate pain as well as all other senses.
Inside, there were numerous signal transceivers. By using the electronic signals sent by those transceivers, the gear accessed the user’s brain itself. The user didn’t use their eyes or ears to see and hear, the signals went directly to their brain. In addition, the machine could access not only sight and sound, but also: touch, taste, and smell as well—that is to say, all five senses.
But the players in SAO apparently don't feel pain except for some discomfort.
Kuradeel wrinkled his brow and curved his lips upwards, then stabbed my right arm with the tip of his sword. He then twisted it twice, then thrice.
“Argh…!”
Although I didn’t feel any pain, an unpleasant feeling of being stimulated in the nerves passed through my entire body alongside the strong paralysis effect. Every time the blade dug into my arm, my HP decreased slowly but steadily.
In ALO Pain Absorption is introduced as a setting that regulates how much pain the player feels from a wound.
The flames coursing through my nerves were extinguished by the sensation of thick metal piercing through my body. The center of my chest was pierced through by the sword, which seemed to be deeply rooted in the floor. Though there was no pain, I was being assaulted by intense discomfort.
“Ki... Kirito-kun!!” Hearing Asuna’s cry, I met her gaze while trying to tell her ‘I’m fine’.
However, faster than my voice could come out, Sugou suddenly spoke out to the darkness in the sky above with a booming voice.
“System command! Pain Absorption, change to level 8.”
That moment, a sharp cone of pure pain spread through my back, as if I was stabbed.
“G... Guh...” When a groan leaked out of my mouth, Sugou howled in laughter.
“Kukuku, there’s still two more treats for you. The pain will get stronger gradually so look forward to enjoying it. When it gets lower than level 3, I’m afraid it seems you’ll still feel the symptoms of shock even after logging out.”
Considering that ALO is based on the SAO technology we can likely assume that this setting was used to prevent the SAO players from feeling any pain.
As to their screams I think that it just natural response when you are in panic and realize that you could/are going to die.
The first and second excerpts are from the first light novel and the last one is from the fourth (translations by Baka-Tsuki).
