There doesn't seem to be much professional literature which delves into the specifics of how cognitive biases can affect our auditory perception, but I did run across this recent paper on "Overcoming Bias: Cognitive Control Reduces Susceptibility to Framing Effects in Evaluating Musical Performance."
https://www.nature.com/articles/s41598-018-24528-3
The paper focuses on how bias can affect perception of quality of music performances, rather than perception of sound quality, but IMO it has some relevance to our topic. The basic finding was that, when a listener is told that a performance is by a professional musician rather than a student musician, listeners will tend to perceive the performance as being of higher quality, and this is a more consistent effect than whether the performance was actually by a professional vs student. They used fMRI to see what was happening with people's brains as they listened, and they found that telling a listener that a performer is a professional tended to cause brain responses within a few seconds which would cause the performance to be viewed more favorably, and those brain responses persisted through listening to 70-sec music excerpts, as well as after listening. These brain responses involved the listeners paying more attention. Once a listener was told that a performance was by a professional, it was difficult for listeners to conclude otherwise, even when the performance provided mounting evidence that it wasn't by a professional.
Again, this test looked at music performance quality rather than sound quality, but we can speculate that similar mechanisms could be at work when we do sighted listening evaluations of DAC/amps. This may tie in with the differences I perceived between the H2 and Mojo effectively disappearing when I listened to the same music excerpts back to back with instant switching, which may have prevented time for biases to kick in. The observation about listeners paying more attention also ties in with my sense (could be wrong) that my attention was heightened when I thought I was listening to the H2 rather than the Mojo. If you guys try these various listening protocols yourself and notice how you make your judgments about sound quality, and your confidence in those judgments, all of this may make more sense to you.
Here are some quotes from the paper:
"By modulating expectations and beliefs, contextual information can alter the enjoyability of stimuli as diverse as artworks, soda, and wine, influencing or even dominating actual sensory perception."
"... contextual information can contribute materially to positive perceptual experiences. Aesthetic experiences sometimes depend on the prior activation of a set of beliefs that dispose a person to perceiving this way—a “preparatory set” consisting of expectations and beliefs. For instance, even though listening to Joshua Bell perform a concert on the violin can cost $100 per ticket, an incognito performance by him at a subway station triggered very little interest. Generally, this evidence suggests that contextual information can affect preferences and perception in both nefarious and beneficial ways."
"Previous neuroimaging studies suggest that the influence of beliefs and expectations arises not merely from the sensory system, but from the particular sensitivity to contextual information of reward structures in the brain."
"Our analysis revealed that, when a piece was preferred, the professional pianist frame induced significantly more activity in the primary auditory cortex relative to the student pianist frame (see Fig.
2A). This suggests that beliefs regarding the quality of a performer engendered a bias in attention."
"We observed higher activation in the primary auditory cortex when the player was described as a professional pianist relative to when the player was described as a student. Moreover, this difference in activity remained consistent, exhibiting no significant changes across the 70 seconds of the excerpt. A panel regression of activity in the primary auditory cortex on time showed no significant linear slope (
b1 = 0.0003,
z = 0.56,
p > 0.5). This supports the notion that a bias in attention began almost immediately (i.e. 4 sec) after the presentation of the framing information and remained stable throughout the evidence accumulation period. Contrary to the notion that more evidence should diminish any framing effects generating during the relatively short framing period (i.e. 4 sec), we found that the professional framing gave rise to a constant
attentional bias in favor of the professional player."
"...as information about the quality of the performance accumulated, participants needed to exert cognitive control in order to form and retain a negative evaluation for performances that had been framed as played by a professional compared to those that had been framed as played by a student. These data suggest that less cognitive effort was required to dislike a performance when it had been described as played by a student rather than a professional."
"... by expecting better performance from a professional, participants directed more attention toward professionally framed pianists compared to the student-framed performances, and therefore, exhibited a heightened tendency to gather more evidence that would confirm their prior expectation about the professional player’s performance."
"From the perspective of music psychology, these findings reinforce the notion that extrinsic factors—outside the borders of the notes themselves—can impact perception and evaluation as critically as the intrinsic characteristics of the acoustic signal."
