Visual encoding( of picture images) and acoustic encoding (of sound) are shallower forms of processing than s semantic encoding (of meaning). We process verbal information best when we encode it semantically, especially if we apply the self-reference effect, making information "relevant to me"
Contemporary researchers are focusing on memory-related changes within and between single neurons. As experience strengthens the pathways between neurons, synapses transmit signals more efficiently. In a process known as long-term pontentiation (LTP), sending neurons in these pathways release neurotransmitters more quickly, and receiving neurons may develop additional receptors, increasing their ability to detect the incoming neurotransmitters. LTP appears to be the neural basis for learning and memory.
