hat does a glance hold, and for how long? George Sperling's doctoral work, published as a monograph in 1960, showed that people see more in a brief flash than they can report, and that the excess fades within about a second.

the document

Sperling, "The information available in brief visual presentations", Psychological Monographs. No free copy that we could verify; the DOI goes to the publisher.

what it says

Participants saw grids of letters for a fraction of a second, shown with a tachistoscope. Asked to report everything (whole report), they managed about four or five letters, however many were shown. Then Sperling played a tone just after the display, high, middle or low, telling them which row to report (partial report). They could report most of any cued row, which implied that most of the whole grid had been available for a moment. Delaying the tone shrank the advantage until, by about a second, partial report was no better than whole report [paraphrase, not a quotation]. Neisser later named the brief store iconic memory (Neisser, 1967).

what's contested

Is the icon seen? Block (2007) and Block (2011) use partial report as central evidence that phenomenal consciousness overflows access: participants say they saw all the letters, and the cue shows the information was there. Cohen & Dennett (2011) reply that a theory of consciousness that cannot, in principle, be tested by report or function is not a scientific theory. Phillips (2011) argues that Sperling's data are consistent with participants seeing only some of the letters well and the rest generically. Kouider et al. (2010) offer the "partial awareness" alternative, and de Gardelle et al. (2009) found people reporting letters that were in fact non-letters, suggesting the sense of richness is partly filled in [paraphrase, not a quotation].

Newer evidence. Retro-cue studies by Landman et al. (2003) and Sligte et al. (2008) found a large-capacity but fragile store lasting longer than the classical icon, which overflow theorists cite; Bronfman et al. (2014) found people registered colour diversity in uncued rows. Haun, Tononi & Koch (2017) argue experience is richer than report-based tasks can show.

methodological critiques

Coltheart (1980) showed that "iconic memory" had been used for at least two different things: visible persistence (the display seems to last) and informational persistence (information remains usable), which behave differently. The bar-probe method of Averbach & Coriell (1961) gave converging evidence. The deeper problem is that every measure of what was seen is itself a report, so the overflow debate is partly about whether any experiment could settle it.

later reception

The partial-report procedure is one of the most replicated in psychology, and the most philosophically loaded. It is the template for asking how much a system holds that it cannot output, a question now put to networks with probes.

References

1. Sperling (1960). The information available in brief visual presentations. Psychological Monographs: General and Applied. doi:10.1037/h0093759
2. Neisser (1967). Cognitive Psychology. New York: Appleton-Century-Crofts.
3. Block (2007). Consciousness, accessibility, and the mesh between psychology and neuroscience. Behavioral and Brain Sciences. doi:10.1017/S0140525X07002786
4. Block (2011). Perceptual consciousness overflows cognitive access. Trends in Cognitive Sciences. doi:10.1016/j.tics.2011.11.001
5. Cohen & Dennett (2011). Consciousness cannot be separated from function. Trends in Cognitive Sciences. doi:10.1016/j.tics.2011.06.008
6. Phillips (2011). Perception and Iconic Memory: What Sperling Doesn't Show. Mind & Language. doi:10.1111/j.1468-0017.2011.01422.x
7. Kouider et al. (2010). How rich is consciousness? The partial awareness hypothesis. Trends in Cognitive Sciences. doi:10.1016/j.tics.2010.04.006
8. de Gardelle, Sackur & Kouider (2009). Perceptual illusions in brief visual presentations. Consciousness and Cognition. doi:10.1016/j.concog.2009.03.002
9. Landman, Spekreijse & Lamme (2003). Large capacity storage of integrated objects before change blindness. Vision Research. doi:10.1016/S0042-6989(02)00402-9
10. Sligte, Scholte & Lamme (2008). Are There Multiple Visual Short-Term Memory Stores?. PLoS ONE. doi:10.1371/journal.pone.0001699
11. Bronfman et al. (2014). We See More Than We Can Report. Psychological Science. doi:10.1177/0956797614532656
12. Haun et al. (2017). Are we underestimating the richness of visual experience?. Neuroscience of Consciousness. doi:10.1093/nc/niw023
13. Coltheart (1980). Iconic memory and visible persistence. Perception & Psychophysics. doi:10.3758/BF03204258
14. Averbach & Coriell (1961). Short-Term Memory in Vision. Bell System Technical Journal. doi:10.1002/j.1538-7305.1961.tb03987.x

see also