High-Fidelity Visual Long-Term Memory within an Unattended Blink of an Eye.

Christof Kuhbandner,Philipp Spachtholz,Elizabeth A. Rosas-Corona

doi:10.3389/fpsyg.2017.01859

Christof Kuhbandner, Philipp Spachtholz + Show 1 more

Open Access

https://doi.org/10.3389/fpsyg.2017.01859

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Abstract

What is stored in long-term memory from current sensations is a question that has attracted considerable interest. Over time, several prominent theories have consistently proposed that only attended sensory information leaves a durable memory trace whereas unattended information is not stored beyond the current moment, an assumption that seems to be supported by abundant empirical evidence. Here we show, by using a more sensitive memory test than in previous studies, that this is actually not true. Observers viewed a rapid stream of real-world object pictures overlapped by words (presentation duration per stimulus: 500 ms, interstimulus interval: 200 ms), with the instruction to attend to the words and detect word repetitions, without knowing that their memory would be tested later. In a surprise two-alternative forced-choice recognition test, memory for the unattended object pictures was tested. Memory performance was substantially above chance, even when detailed feature knowledge was necessary for correct recognition, even when tested 24 h later, and even although participants reported that they do not have any memories. These findings suggests that humans have the ability to store at high speed detailed copies of current visual stimulations in long-term memory independently of current intentions and the current attentional focus.

Highlights

Imagine that you are walking along a street together with a friend, focusing your attention completely on your conversation
In view of the apparent problem that an overwhelming amount of information would have to be stored and handled if all of the information reaching our senses at any moment persisted in memory, common wisdom over time has been that only a small part of the information leaves a durable memory trace whereas the rest is quickly lost, an assumption that is reflected in prominent theories which have been developed over time (e.g., Atkinson and Shiffrin, 1968; Wolfe, 1999; Cowan, 2001; Lavie, 2010)
In the delayed recognition test, even when memory for the objects was the first time tested after a delay of 24 h, still substantial memory was found (Novel: M = 20.5%, 95% CI [12.4, 28.6], t(39) = 5.00, p < 0.001, d = 0.81; Exemplar: M = 8.3%, 95% CI [2.2, 14.3], t(39) = 2.59, p = 0.007, d = 0.44; State: M = 13.5%, 95% CI [7.1, 19.9], t(39) = 4.10, p < 0.001, d = 0.67)

Summary

Introduction

Imagine that you are walking along a street together with a friend, focusing your attention completely on your conversation. Your eyes wander around, randomly fixating for less than a second on visual objects passing by, without you noticing the information that reaches your eyes at all. Twenty-four hours later, someone asks you unexpectedly about your memories for the objects your eyes had briefly fixated on during that walk. If you remembered any object at all, how detailed would the memory be? The question of what is stored in long-term memory from current sensations has intrigued humans for centuries (e.g., Burnham, 1888; Loftus and Loftus, 1980). In view of the apparent problem that an overwhelming amount of information would have to be stored and handled if all of the information reaching our senses at any moment persisted in memory, common wisdom over time has been that only a small part of the information leaves a durable memory trace whereas the rest is quickly lost, an assumption that is reflected in prominent theories which have been developed over time (e.g., Atkinson and Shiffrin, 1968; Wolfe, 1999; Cowan, 2001; Lavie, 2010)

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