Category: Inattentional Deafness

Gorillas we have missed: Sustained inattentional deafness for dynamic events.

Dalton, P., & Fraenkel, N. (2012). Gorillas we have missed: Sustained inattentional deafness for dynamic events. Cognition124(3), 367-372.

The ability of selective attention is a crucial ability that allows us – and only that way  – to behave effectively in a world full of simultaneous stimuli.

Following the inattentional blindness paradigm, the authors focused on hearing,since it is considered an early warning system, tuned to detect unexpected stimuli. Is it rightly tuned?

In order to replicate the effect in hearing, Dalton and Fraenkel dissecated the inattentional blindness paradigm into three components:

1. A task relevant stimuli

2. A task irrelevant stimuli

3. An unexpected critical stimulus

This last ingredient should be similar to the irrelevant stimuli only in the dimension that differed them both from the relevant stimuli. However, they should differ from each other in other dimensions such as spatial location, speed, trajectory, shape, etc.

Having said this, the intriguing thing of the inattentional deafness effect is that “the similarity between the unexpected critical stimulus and the irrelevant stimuli on the dimension upon which relevant and irrelevant are defined, can prevent the detection of the critical stimulus, despite its salience on a number of other dimensions” (note to self -> is this somewhat molded by expectations? Are we tuned to expect some things based on experience (we are!), and does this speed up processing? Expectations as a tool to process the world faster.)

This doesn’t seem very efficient, because in real world situations, processing new and unexpected stimuli – fire alarms, unexpected movements – is likely to be more important than processing of continually present yet task irrelevant scene elements.

The twist on this experiment was that the authors used binaural sound to provide a realistic audio scene and the critical stimuli was dynamic. When thinking about the dichotic listening task, this set up makes spatial separation harder.


So, two men and two women were separately placed in a room, preparing a party. The dummy head was placed between these two tables. A man saying “I am a gorilla” passed near the men.This was the critical stimulus and it lasted for 19s.

In both experiments, the channels were reversed for half of the participants in order to balance for potential orientation effects.

In experiment 1, the gorilla passed near the men. Results showed that 90% of the participants attending to men’s conversation mentioned the gorilla. However, only 30% of the participants attending to the women’s conversation mentions the gorilla.

In experiment 2, the gorilla was presented in “mirror image”, such that it appeared on the other side of the screen, passing near the women. This was somewhat more flagrant than experiment 1 in the sense that the critical stimulus was near the relevant stimulus, and was different at least in the voice tone.

This time, 65% of the participants listening to men mentioned the gorilla, while only 45% listening to women mentioned it.

The results showed relevant evidence for the inattentional deafness effect with dynamic stimulus in 3D audio scenes. This finding can have serious implications in road safety.

Hopefully, more on that later.


Visual perceptual load induces inattentional deafness

Macdonald, J. S., & Lavie, N. (2011). Visual perceptual load induces inattentional deafness. Attention, Perception, & Psychophysics73(6), 1780-1789.

This seems to me to be the first paper on the subject, dating from 2011. The idea was to verify whether perceptual capacity is modality specific or not. The method was rather simple and low-tech, which is different from what I have been reading. And refreshing for that matter! Once again, the authors – who first brought attention to the inattentional deafness concept – modified an inattentional blindness paradigm to assess inattentional deafness.

The authors say that focused attention on a task results in reduced perception of irrelevant information. This reduction depends on the level of the perceptual load in the task. Perceptual load corresponds to the amount of information involved in the perceptual processing of the task stimuli. Tasks involving higher perceptual load consume all or most of attentional capacity, leaving little or none remaining for processing any task irrelevant information. In this scenario, the authors ask, would a car horn be noticed when you were attending to a visually loaded billboard?

They wanted to see whether perceptual load in a visual attention task would modulate conscious awareness of task unrellated auditory tones.

For that, a set of three experiments were made, all with a very similar set-up and procedure.




In the low load task, the participant had to signal which arm of the cross was blue.

In the high load task, the participant had to signal which arm was longer. By the end of the eighth trial, a critical audio sign (CS) was played, and by the end of the task the participant was asked if s/he noticed anything different from previous trials.

For experiment 1, white noise was played continuously for 19s during each trial. In the critical and control trials, a 180 Hz pure tone at 28 dB of either 100 or 150ms was presented at the onset of the cross.

The participants were later asked to describe the experiment, even when they have not noticed anything different.

The results demonstrated that error rates were significantly higher in the high load condition than in the low load condition. 7 out of 28 participants reported awareness in the high load condition, whereas 21 out of 28 noticed something different in the low load condition. These results show that, in fact, the tasks differed as for mental load, and what’s more, that the effect of inattentional deafness was indeed verified.

Experiment 2 wanted to assess to what extent could the phenomenon be verifies, so the authors removed the white noise, leaving the critical audio sign unmasked.

Again, both high and low load conditions differed significantly in error rates. In the high load 5 out of 24 noticed the sign, and in the low load, 21 out of 24 noticed it.

This means that high perceptual load in a visual attentional task reduces auditory awareness, thereby producing inattentional deafness, even with an unmasked tone and when people are not actively ignoring sound.

Experiment 3 randomly intermixed the high and low task within a longer block of 143 trials. Also, the low load task was changed to a line length discrimination task with a far greater line length difference than in the high load condition. Like in experiment 2, no white noise was played.

In this experiment, the reaction times were significantly longer in the high load condition, and error rates were also higher in the high load condition. 18 out of 32 reported awareness in the high load condition, and 28 out of 32 reported it in the low load condition. These surprising results got the authors to the conclusion that inattentional deafness was influenced by the level of visual perceptual load in the task rather than by any differences in motivation, vigilance, task engagement, or strategy.


All in all, results suggested that the elementary process of noticing the mere presence of a sound depends on an attentional capacity resource that is shared between the modalities of vision and hearing.

The authors claim that it is possible that some processing capacities are modality specific, while others draw on a shared cross-modal resource. For example, previous findings that perception of visual motion is reduced by attention to a high load visual stimulus stream, but not to an auditory word stream, may indicate that the perception of visual motion suffers from visual capacity limits.

Inattentional deafness under dynamic musical condition

Koreimann, S., Strauß, S., & Vitouch, O. (2009). Inattentional deafness under dynamic musical conditions.

Also sprach Zarathustra (Strauss)

Yesterday as I was scrolling through my feeds I noticed an interesting concept I’ve never heard before: Inattentional Deafness. It makes sense if one thinks about it, but I’ve never seen this term, even while reading about Inattentional Blindness and Cognitive Tunneling.

So I just started researching on the subject and this week I’ll be digging deeper into it.

This text is a proceeding from the 7th Triennial Conference of European Society for the Cognitive Sciences of Music (ESCOM 2009).

Remember this post? Neisser was the first to demonstrate the phenomenon of inattentional blindness, although not using the term. The term was later coined by Mack and Rock (1998), who demonstrated that the inattention awareness phenomena are by no means restricted to vision.

Inattentional Deafness happens when a particular auditory stimulus remains unnoticed.

The authors of this study wanted to replicate the gorilla experiment but using audio stimuli. They used the opening of “Thus spoke Zaratustra” from Strauss, and edited it so that at 1:16s, 20s of an electric guitar solo were embebed in the audio file. The authors used two different audio, one with the main take of the piece, and another alternate take, edited in order to be simpler, and with more noticeable modifications.

Non-musicians and amateur musicians were used in this experiment. The task of the experimental group was to count the number of tympani beats in the piece. By the end of the listening phase, participants were asked if they noticed anything peculiar, if any unfitting sounds or instruments were noticed and, finally, if they noticed an e-guitar.


In the Main Take, in the non-musicians group only one person mentioned explicitly the e-guitar. In the control group 52% of the participants noticed it. As for the amateur musicians, the results were less extreme, although 38% of the participants noticed the guitar, compared to 68% from the control group. A significant difference between non and amateur musicians was found.

In the Alternate Take the authors used only non-musicians. Participants performed better, although the inattentional deafness effect was still present.

This meant that the effect is moderated by the difficulty of the attended task. Another interesting finding, according to the authors, was the presence of the inattentional deafness effect in domain-specific experts, which hasn’t been found/done before in the context of inattentional blindness.