Following up on "Psycho kids today", here's a passage from Kali Trzesniewski and M. Brent Donellan, "Rethinking 'Generation Me': A Study of Cohort Effects From 1976-2006", Perspectives on Psychological Science 5(1) 2010:
Social commentators have argued that changes over the last decades have coalesced to create a relatively unique generation of young people. However, using large samples of U.S. high-school seniors from 1976 to 2006 (Total N = 477,380), we found little evidence of meaningful change in egotism, self-enhancement, individualism, self-esteem, locus of control, hopelessness, happiness, life satisfaction, loneliness, antisocial behavior, time spent working or watching television, political activity, the importance of religion, and the importance of social status over the last 30 years.
They criticize studies like those of Konrath and Twenge:
The results of these meta-analytic studies are provocative; however, the cross-temporal meta-analytic technique for identifying cohort-related changes in psychological characteristics is limited in terms of how the method is usually applied to the existing literature (Arnett, in press; Trzesniewski, Donnellan, & Robins, 2008a). Foremost, the generalizability of these findings is simply uncertain because the samples typically included in the meta-analyses are not designed to make population inferences. The concern is that the constituent samples are often generated using nonprobability sampling techniques. For instance, it is common for researchers in social and personality psychology to use convenience samples in research, such as undergraduates in introductory courses who participate in research in exchange for course credit. These samples provide data quickly and in large numbers, but the individuals in the sample are not selected at random and they are not representative with respect to a defined population of interest. In these cases, it is not possible to estimate sampling errors or otherwise defend generalizations based on the sample (Pedhazur & Schmelkin, 1991). Increased sample sizes cannot compensate for the limits on inference posed by nonprobability sampling techniques.
Trzesniewski and Donellan's own data comes from the Monitoring the Future project, which follows a careful sampling procedure that "results in an area probability sample of the 48 coterminous states".
Their paper opens with a quotation falsely attributed to Socrates: "Children today are tyrants. They contradict their parents gobble their food, and tyrannize their teachers", noting that "It is seemingly axiomatic that every generation expresses concerns about the qualities of the next generation." Trzesniewski and Donellan resist the temptation to add the quotation often mis-attributed to Peter the Hermit (12th century):
The world is passing through troublous times. The young people of today think of nothing but themselves. They have no reverence for parents or old age. They are impatient of all restraint. They talk as if they knew everything, and what passes for wisdom with us is foolishness with them. As for the girls, they are forward, immodest and unladylike in speech, behavior and dress.
But they do allude to Tom Wolfe, "The ‘Me’ Decade and the Third Great Awakening", New York Magazine 8/23/1976, and Christopher Lasch, "The Culture of Narcissism", 1979. And there are plenty of genuine older examples of the trope, some cited in "Kids today", 3/11/2010.
For an old idea about why "young people today think only of themselves" might be an especially resilient form of the o tempora o mores trope in the United States, we turn to Alexis de Tocqueville, Democracy in America, Volume 2, 1840:
I have shown how it is that in ages of equality every man seeks for his opinions within himself. I am now to show how it is that in the same ages all his feelings are turned towards himself alone. Individualism is a novel expression to which a novel idea has given birth. Our fathers were only acquainted with égoïsme (selfishness). Selfishness is a passionate and exaggerated love of self, which leads a man to connect everything with himself and to prefer himself to everything in the world. Individualism is a mature and calm feeling, which disposes each member of the community to sever himself from the mass of his fellows and to draw apart with his family and his friends, so that after he has thus formed a little circle of his own, he willingly leaves society at large to itself. Selfishness originates in blind instinct; individualism proceeds from erroneous judgment more than from depraved feelings; it originates as much in deficiencies of mind as in perversity of heart.
Selfishness blights the germ of all virtue; individualism, at first, only saps the virtues of public life; but in the long run it attacks and destroys all others and is at length absorbed in downright selfishness. Selfishness is a vice as old as the world, which does not belong to one form of society more than to another; individualism is of democratic origin, and it threatens to spread in the same ratio as the equality of condition.