I formulate a hypothesis that left-leaning people suffer from Social Desirability Bias on issues of race and gender and I propose an experiment to evaluate my claim.
I'm almost certain that you're right that this bias would be reflected in any survey you put to people on the left. I do have concerns with the framework in this case though: this is a real effect, true enough, but the analysis and terminology of the heuristics and biases program sort of gets in the way here. Talk about "bias" suggests to me some sort of cognitive error, a failure of rationality if you will, even if the term technically just means "tendency of the system to return output in direction X". The way I see it, the issue here is twofold – I believe the proximal reason for people to give biased answers to questions of this nature comes down to the following:
1. They don't actually know themselves well enough to answer the questions truthfully since the mind seemingly isn't designed for self-awareness and introspective transparency
2. They are very likely to substitute the factual question ("Are you more/less biased than the average person?") for a normative one ("Are you a better/worse human being than the average person?") or a question about their current emotional state ("How do you feel about the idea that you may be biased?") and then proceed to answer that question as truthfully as they can
People in general have a strong aversion to seeing themselves as morally inferior and the purpose of a "self-image" is not to portray yourself as accurately as possible but to make the best impression possible, i.e. the whole idea of a stable self with certain fixed characteristics is to a large degree about signalling, which results in precisely this type of self-serving bias in self-appraisal.
So, in short the most economical explanation for this bias is simply that people aren't aware that they are in error and aren't even trying to be factually accurate in the first place. Framing it as a bias might give the impression that they are trying and failing to give factually correct responses whereas I believe they are rather succeeding at a separate task, namely to (truthfully) signal their moral status to the questioner.
I'm almost certain that you're right that this bias would be reflected in any survey you put to people on the left. I do have concerns with the framework in this case though: this is a real effect, true enough, but the analysis and terminology of the heuristics and biases program sort of gets in the way here. Talk about "bias" suggests to me some sort of cognitive error, a failure of rationality if you will, even if the term technically just means "tendency of the system to return output in direction X". The way I see it, the issue here is twofold – I believe the proximal reason for people to give biased answers to questions of this nature comes down to the following:
1. They don't actually know themselves well enough to answer the questions truthfully since the mind seemingly isn't designed for self-awareness and introspective transparency
2. They are very likely to substitute the factual question ("Are you more/less biased than the average person?") for a normative one ("Are you a better/worse human being than the average person?") or a question about their current emotional state ("How do you feel about the idea that you may be biased?") and then proceed to answer that question as truthfully as they can
People in general have a strong aversion to seeing themselves as morally inferior and the purpose of a "self-image" is not to portray yourself as accurately as possible but to make the best impression possible, i.e. the whole idea of a stable self with certain fixed characteristics is to a large degree about signalling, which results in precisely this type of self-serving bias in self-appraisal.
So, in short the most economical explanation for this bias is simply that people aren't aware that they are in error and aren't even trying to be factually accurate in the first place. Framing it as a bias might give the impression that they are trying and failing to give factually correct responses whereas I believe they are rather succeeding at a separate task, namely to (truthfully) signal their moral status to the questioner.
You might be interested in the https://en.wikipedia.org/wiki/Unmatched_count technique used in "Do Americans Really Support Black Athletes Who Kneel During the National Anthem? Estimating the True Prevalence and Strength of Sensitive Racial Attitudes in the Context of Sport " study https://journals.sagepub.com/doi/abs/10.1177/21674795211019670
I need to say "median" rather than average.