A Picture is Worth a Thousand Words

  Our ``draw-a-secret'' scheme is motivated by the experimentally-proven fact that pictures are easier to remember than words. Why are pictures easier to recall? Four hypotheses have been offered as explanations of picture-word differences in recall:

• Common-code theory: this view of memory and recall theorizes that pictures and words access semantic information in a single conceptual system that is neither word-like or picture-like. This theory hypothesizes that pictures and words both require analogous processing before accessing semantic information, but pictures require less time than words for accessing the common conceptual system. Common-code theorists attribute better picture recall to differences in the encoding of pictures and words: pictures share fewer common perceptual features among themselves and therefore need to be discriminated from a smaller set of possible alternatives than words. The greater number of dictionary meanings or the greater lexical complexity of words create uncertainty and confusion, and hence poorer recall.
• Dual-code theory: unlike the common-code approach, this theory postulates that language and knowledge of worlds are represented in functionally distinct verbal and nonverbal memory systems. The verbal system is specialized for dealing with linguistic information whereas the non-verbal stores perceptual information. The most evident examples of dual process theory can be found in experiences that we have all had at some time or the other: we meet someone, know them to be familiar but do not know who they are; we recognize a melody, but fail to remember its name or when or where we heard it before; we read a line of a poem, know it, but do not know where we have read it before, much less the title or author of the poem. In all these cases, we experience a sense of familiarity, but have -- at least at first -- no access to any contextual or conceptual information  [17].

  Dual code theory suggests that there are qualitative differences between the ways words and pictures are processed during memory and hypothesizes that the reason for superior picture memory is that pictures automatically engage multiple representations and associations with other knowledge about the world, thus encouraging a more elaborate encoding than occurs with words  [25,23].

• Abstract-propositional theory: in contrast to the dual-code approach, this theory rejects any notion of sophisticated distinctions between verbal and nonverbal modes of representation, but instead describes representations of experience or knowledge in terms of an abstract set of relations and states, called propositions. This theory postulates that better free recall with pictures may be due to even more elaborative encoding effects than those suggested by dual-code theorists. Propositional theorists view the involvement of abstractive and interpretive processes in picture memory as the explanation for the picture effect [15]. Therefore, a series of line drawings will be poorly remembered if a subject is unable to interpret the drawings in a meaningful way, whereas memory for the same drawings, presented in the same way will be much better if a conceptual interpretation is provided, and it this interpretive process which is responsible for better picture memory recall.

While the strongest evidence thus far for the picture effect can be best explained by dual-code theory (see [17]), an understanding of picture memory and the means by which we acquire and maintain information about the visual environment is still an ongoing challenge. Nonetheless, the research to date provides strong arguments in terms of the memorability of drawings over words in recognition tasks and hence its applicability to computer security.