A short description of current thinking may be helpful in order to put auditory memory in perspective (see also 3.2, 3-3)_ Potter (1990) distinguishes between three kinds of short-term memory: iconic, very short-term conceptual, and short-term verbal memory. Potter notes that these three types Of memory are subject to differing types of interference and differing rates of forgetting. Iconic memory serves as a short-term visual buffer. It recognizes objects in 200 to 300 milliseconds and then holds that information for about 200 milliseconds. Very short-term conceptual memory receives scenes from iconic memory and stores diem temporarily in conceptual form. These memories are not interfered with by iconic memory, but may be by other conceptual tasks. Very short-term conceptual memory decays in about I second. If these concepts are not embedded into a train of thought, they are lost. Finally, we have short-term verbal memory. This memory consists of an auditory buffer, which is severely limited in its capacity but may be maintained by continuous rehearsal. Its capacity is about 1.3 to 1.7 seconds, and its decay rate is nearly the same, allowing us to "replay" words or sounds heard a short time before. Meaningful background noise can interfere with verbal memory, and because this buffer is used for understanding written text, interference between the two channels may be experienced. This relates to the multichannel theories of learning that will be discussed later.