The present findings suggest that denigrating today’s youth is a fundamental illusion grounded in several distinct cognitive mechanisms

Hmmm. A few years ago I blogged The new generation is indeed not the equal of its progenitors commenting on the ages-old Curmudgeon's Lament (kids these days . . .) and a way to see that it might have some validity.

My alternative or supplemental explanation of the Curmudgeon's Lament is that 1) civilizations rise and fall, 2) they produce more literature at the apex or just past the apex when they are declining, 3) higher production volume leads to disproportionate survival, 4) written at the time of decline, the children likely were inferior to those who built the civilization. Therefore, the plaint of kids these days is an artifact of a survival bias of complaints.

Someone has actually done some research to try and quantify the Curmudgeon's Lament. From Kids these days: Why the youth of today seem lacking by John Protzko and Jonathan W. Schooler. From the Abstract:

In five preregistered studies, we assess people’s tendency to believe “kids these days” are deficient relative to those of previous generations. Across three traits, American adults (N=3,458; Mage = 33-51 years) believe today’s youth are in decline; however, these perceptions are associated with people’s standing on those traits. Authoritarian people especially think youth are less respectful of their elders, intelligent people especially think youth are less intelligent, well-read people especially think youth enjoy reading less. These beliefs are not predicted by irrelevant traits. Two mechanisms contribute to humanity’s perennial tendency to denigrate kids: (1) a person-specific tendency to notice the limitations of others where one excels, (ii) a memory bias projecting one’s current qualities onto the youth of the past. When observing current children, we compare our biased memory to the present and a decline appears. This may explain why the kids these days effect has been happening for millennia.

The discussion part of the paper is actually more revealing than the abstract.

In five studies, we found evidence of a general tendency to disparage the present youth across traits (respect for elders and enjoying reading) and a trait-specific tendency to see today’s youth as especially lacking on those traits on which one particularly excels (respect for elders, intelligence, and enjoying reading). Although the trait specificity of the kids these days effect was observed across three domains, there was no impact of excelling on a trait other than the one in question. Someone who has a high respect for authority is especially likely to believe that kids these days no longer respect their elders, but not necessarily that kids these days are in decline in other ways (e.g., becoming less intelligent). We also found indirect evidence for at least two mechanisms underpinning this effect. First, people who objectively excel in a dimension are more likely to notice others’ failings on that dimension, for both the youth and adults of the day. In addition, excelling on a dimension also leads people to project back to both themselves and their peers in the past, believing, for example, “because I like to read now everyone liked to read when I was a child.” Manipulating this subjective belief, partialing out objective standing, causes a reduction in the kids these days effect through this proposed mechanism. Apparently, when observing current children, we compare our biased memory of the past to a more objective assessment of the present, and a natural decline seems to appear. This can explain why the kids these days effect has been happening for millennia.

This backward projection from the self to kids likely occurs because people have fewer details available when recalling past peers than when assessing present adult peers. People use their present self as a proxy for their past self as well as projecting onto past others. When judging present others, we have readily available information and do not need to rely so much on self-projections. The causal effects shown in study 5, however, were small, suggesting additional mechanisms of the kids these days effect to those explored here.

The present findings suggest that denigrating today’s youth is a fundamental illusion grounded in several distinct cognitive mechanisms, including a specific bias to see others as lacking in those domains on which one excels and a memory bias projecting one’s current traits to past generations. It may be the case that, in some domains, children really have been in decline; in which case, our findings also highlight how accurate perceptions of declines relate to individuals’ standing on those traits. Although we cannot rule out actual declines, it is likely that part of the kids these days effect is illusory. In some domains (e.g., intelligence), children are increasing (13), and there is no objective reason more intelligent people would falsely believe the opposite. Although increases in intelligence have stalled in some countries, even reversing in some Nordic countries, in the United States, where these participants are from, intelligence continues to rise (15). Furthermore, in other domains (e.g., reading and respect for elders), the same complaints have been leveled against youth of the day for the past 2500 years; this would imply a steady deterioration over millennia, which seems highly unlikely. We find that perceptions of a decline in today’s youth can be experimentally manipulated by altering people’s memories of themselves as children. Although the cognitive mechanisms that unfairly impugn children today are likely to persist for millennia to come, knowledge of their sources may minimize unwarranted gloom about future generations.

Yep, cognitive mechanisms lead to the Curmudgeon's Lament. The survivorship bias cannot be ruled out based on this research. Real declines cannot be rule out either.

The trait bias is an interesting discovery. That reader's think kids don't read as much, that authoritarian personalities think kids don't have as much respect, etc.