Reaction to “A mechanical model for human attention and immediate memory” by Broadbent (1957)

Reaction to Broadbent (1957) by Richard Thripp
EXP 6506 Section 0002: Fall 2015 – UCF, Dr. Joseph Schmidt
September 15, 2015 [Week 4]

Broadbent (1957) presents a model for human attention conceptualized as a Y-shaped tube that receives balls that represent information. A flap divides the Y-connection, and various parallels between what would happen to the actual balls and to human attention and memory are proposed.

Broadbent could instead have used water flowing through a Y-connector as his analogy—the rate or constriction of flow could vary between pipes, for example. There are many analogies that could be used. Whether this is a good analogy is up for debate, but seeing that Broadbent had to attach numerous codicils (p. 206, 208, 210) and discusses many limitations (p. 213) and conceptual problems with his model seems to suggest it is questionable. His modified model in Figure 2 (p. 210) appears as a circuit, which models memory as a recurrent process, but is admittedly an unwieldy and difficult model, given the author’s humorous comments that the apparatus would need to be filled with acid to replicate the disappearance of a memory item by dissolving a ball. This model might be more detrimental than useful as a teaching tool, if it results in profound, lasting misconceptions. The author admits: “Certain properties of the model are likely to be misleading” (p. 213)—no kidding! I can only imagine that getting this published in 1957 was much easier than it would be now.

We are familiar with the idea of “semantically impoverished” stimuli—that stimuli such as colored boxes and abstract shapes are not as salient as real-world stimuli. When Broadbent clarifies that stimuli can bypass the Y tube “if they convey sufficiently little information” (p. 213), one wonders if he considered the distinction between semantically rich and semantically impoverished stimuli? Being that he goes on to discuss reflexes and generalize them to “voluntary” reactions, it appears the distinction was (momentarily) lost on him. Broadbent may have been a visionary if he replaced “convey[ing] sufficiently little information” with something like “requiring sufficiently little processing resources.” The quantity of information is not always the most important part—later on the same page, Broadbent makes the point that decimal digits (base 10) convey far more information than binary digits (base 2), and yet do not require much (or any) extra effort for our brains to remember (p. 213). Therefore, the Y tube model is grossly oversimplified—some balls may in fact be bigger than others, and some may require negligible resources.

Broadbent concedes the Y tube analogy is of “obvious absurdity” if one identifies it with the organism, rather than as a mechanical conceptualization for human attention and immediate memory (p. 213). He proposes the model is primarily for people who find the abstract theory “unintelligible”—and indeed, it may help them. However, individuals who have a rudimentary understanding of attention and memory may be better off skipping Broadbent’s paper, given that it may imbue them with gross simplifications, rather than refining their understanding.


Broadbent, D. E. (1957). A mechanical model for human attention and immediate memory. Psychological Review, 64(3), 205–215. doi:10.1037/h0047313

Leave a Reply

Your email address will not be published. Required fields are marked *