Explicit and implicit learning

Explicit (Declarative)	Implicit (Procedural)
facts and experiences	skills and habits, priming, classical conditioning
knowledge can be verbalized (conscious)	knowledge is inaccessible (unconscious)
tested by recall, recognition, cued recall (as in school)	evidenced via altered dispositions, preferences, judgements, behavior
one trial learning	often acquired gradually over multiple trials
requires effort and intention.....	acquired incidentally (without intention, attention, or awareness)
flexible knowledge, available to multiple response systems	inflexible knowledge, limited to response systems participating in original learning
not durable	durable
can form conjunctions between arbitrary stimuli (e.g., paired associate learning)	cannot learn conjunctions
“specialized to detect variance, i.e., what is different or unique about the events of a particular time and place” [Eichenbaum].....	“specialized for detecting invariance, i.e., for extracting what is common in stimulus environment” (i.e., regularities)
medial temporal lobe (hippocampus)	striatum (basal ganglia)
source: Learning and Memory

Various:

• I always remember the meaning of "declarative knowledge" by the sentence: "I declare that Abraham Lincoln was the 16th president of the United States." Or: "I declare that I was born in Springfield, IL." Declarative knowledge is facts and factoids you can (consciously) declare.
• I think these two systems correspond to Daniel Kahneman's System 1 and System 2. (Take that with a grain of salt.)
• It's misleading to characterize implicit learning as strictly procedural. Category learning and probabilistic learning are both handled by the basal ganglia. It's the basal ganglia that allow you to learn that where there is smoke, there is fire.
• It's the hippocampus that allows you to learn the aphorism "Where there's smoke, there's fire."
• The basal ganglia-frontal circuit understands language. Procedural memory processes grammar; declarative memory learns vocabulary. 
• "One trial learning" is a bit misleading (in column one). Declarative knowledge can be acquired in one trial in a way that procedural knowledge (e.g.: how to hit a tennis ball) cannot. But retaining declarative knowledge over time requires spaced repetition and practice.
• Not sure about 'cannot learn conjunctions [8th row].' Offhand, it doesn't jibe with scenarios like the weather prediction task. update 8/1/2012: paired-associate learning at Cambridge Brain Sciences - vocabulary learning is a case of paired-associate learning
• Must determine the meaning of "limited to response systems participating in original learning."
• Alzheimer's affects the hippocampus.

And:

Seems to me constructivism mixes these two systems up.

The basal ganglia are built to look for a pattern naturally and unconsciously. You don't have to think about it, and you don't have to go to school to do it. But constructivists want students to expend a great deal of time and conscious effort figuring out the patterns and regularities in school subjects.

Meanwhile declarative knowledge has to be attended to and consciously acquired, but constructivists seem to want students to learn content knowledge more or less by osmosis. Osmosis is the basal ganglia's department. Ditto learning by doing.

Constructivists seem to want to make easy things hard and hard things easy.