Oh gosh... there is SO many things going on at this age.
NO NO NO... "distraction" or "redirection" does NOT mean you are "giving in" to him! A child is not a little adult... it pains me when a baby/toddler is "expected" to know all the wiles of the world... but not allowed to "practice" them or to explore their voice or tactile experiences.
Here's a good book (you can get it from Amazon.com):
"Your One-Year-Old: The Fun-Loving, Fussy 12-To 24-Month-Old" (Paperback)
by Louise Bates Ames (Author), Frances L. Ilg (Author)
ALSO, keep in mind, that a baby/toddler/child is STILL developing their emotions...they don't come fully-loaded with all senses and emotions.... it develops over time. AND they do NOT understand the abstractness of the emotions...nor the "correct" way to react to it. THUS, they are experiencing frustration/anger/humor/curiosity all at the SAME time! YES it's normal that at his age, he "laughs" at his punishment... and NO you don't "time-out" an 18 moth old. My opinion.
PLUS, a child this age does NOT have "impulse control." FULL impulse control does not develop until about 3+ years old.
My son and daughter did that too... laugh at things when WE get frustrated with their voices/actions. They are only beginning to "learn" about facial expressions as well... and the "names" of feelings.
What I did and do with both my kids, even from this age...is I taught them ABOUT facial expressions.... and showed them pictures- ie: happy, sad, grumpy,frustrated, funny etc. Or, I showed them with my own face contortions. THEN, I taught them the "names" for feelings... and you know what? My kids are keenly aware now, of what THEIR feelings are, and my girl was far more articulate and understanding of her own feelings, and what others were feeling. It's a process... it's not just about "discipline"... but "teaching" them... and then allowing for transgressions and learning curves, and their "blossoming" of understanding along the way.
Kids need to know and learn that they have a "voice." Sure, but sometimes it's just irritating, right? Well, choose your battles...but, also know that a child has to learn to communicate with US, and not just the other way around. Teach him... "inside voice" and "outside voice"... my kids have very loud trumpet voices which resonate thru walls and they are very emphatic...but as I tell my Husband "at least if they are ever in trouble or lost in a store.... we will be sure to hear them, because they KNOW how to call out for us and they KNOW they have good strong voices... " Ha, ha.
really though, all kids get frustrated and yell or scream... especially as he is approaching the 2's. But, work on it... teach him HOW to PROBLEM SOLVE so he doesn't get frustrated. For example: he yells because his toy truck flipped over & doesn't roll anymore... well then go to him, SHOW him how to correct it & turn it over... talk slowly and calmly... then show him how. Teaching a child "problem solving" no matter how young, REALLY helps them now and in the future. When my kids have a "problem" & scream.... I say "oh, you can't color because you don't have your crayon?" "Hmmm, well what can you do?" (Then I see their wheels turning)- then I say "where is your crayon? Can you get it yourself?" Then they KNOW they can, and they do it... and they don't "have to" scream for Mommy each time. Whenever some "scream" event happens, I always say "problem solve... think...." and often my eldest child comes up with very creative ways of solving her "temporary" hissy fits.... and I am very proud of her. Even my 26 month old boy is getting the hang of it. It's a good thing to teach them, and later for when they are in school age.
Mostly though, of course help/nurture them anytime they need it. But, not every "scream" demands a "discipline" or heavy-hand to it. Sometimes, just wait a moment... and you don't have to sprint to every tantrum. Just try to talk him through it too.
There's so many "methods" you will hear about... but this is just my 2 cents worth.
Good luck,
Susan