276 III. DEvELOPMENT
striking lack of longitudinal research testing 
whether these mechanisms play out in the 
expected way, and this constitutes one of the 
more serious empirical omissions in the field 
of personality development.
Within the one transaction leading to 
change, we have in the past identified a set 
of change mechanisms contained therein, 
such as standard reinforcement factors, and 
social-  cognitive factors, such as observing 
others (Caspi & Roberts, 1999; Roberts & 
Caspi, 2003). If the evidence for continuity- 
promoting factors is weak, then the evidence 
for change factors is even weaker. Many of 
the mechanisms of change appear to be quite 
obvious (how could anyone doubt that ex -
pectations bring rewards and punishment 
contingencies that shape behavior?), so this 
is surprising. Behaviorists have shown that 
we can mold behavior using different sched -
ules of reinforcement and punishment, yet 
personality psychology has failed to demon -
strate that such contingencies actually shape 
personality. Why?
Instead of testing these mechanisms of 
change, researchers have instead tested the 
associations between demographic and 
“experiential” variables and longitudinal 
changes in personality traits. This may 
be consistent with many of the person– 
environment transactions outlined in the 
neo- socioanalytic model, but none of these 
types of studies have looked more closely at 
the mechanisms of change. The potential ef -
fect of listening to someone’s feedback, or 
the experience of punitive factors over time, 
on personality trait change has essentially 
gone untested in longitudinal research. Even 
in research that examines the effect of in -
terventions, such as therapy on personality 
trait change, the mechanistic features of the 
intervention are typically glossed over (Rob -
erts, Luo, et al., 2017).
In summary, both the mechanisms of con -
tinuity and the mechanisms of change have 
been studied insufficiently. It is easy to accept 
the basic premises behind the mechanisms, 
and selection and socialization processes 
have been studied in laboratory settings to 
demonstrate short-term behavior change. 
But those who study personality develop -
ment have failed to follow up on the short-
term selection and socialization processes to 
look at their effects on long-term continuity and change. To further the study of person -
ality development, we need to investigate 
more deeply the person–  environment trans -
actions and the lower-order mechanisms 
behind continuity and change in personality 
traits.
Conclusion
We have provided in this chapter an update 
to the global view of personality develop -
ment that has supported both the creation 
of the neo-  socioanalytic model of personal -
ity development and the testing of many of 
its ideas. The neo-  socioanalytic model was 
initially mostly descriptive—  it described 
personality and personality development to 
capture more fully new findings that were 
inconsistent with existing frameworks. This 
goal rendered, and continues to render, the 
neo- socioanalytic model as a useful frame -
work, because other frameworks fail to cap -
ture as fully the broad scope of domains of 
personality psychology and the associated 
developmental patterns in those domains. 
The neo-  socioanalytic model contains test -
able hypotheses—  the principles of person -
ality development and the mechanisms of 
continuity and change—  but more clear ar -
ticulation of those ideas is needed. Also, the 
neo- socioanalytic model fails at parsimony. 
Currently, the model’s focus is on personal -
ity trait development, but once it expands 
to accommodate the landscape of abilities 
and motives, it will certainly become even 
more complex. But we have found that the 
neo- socioanalytic model is excellent for the 
generation of new ideas—  currently, more 
ideas have been generated than tested. Over -
all, the neo-  socioanalytic model is a useful 
model that has much room for improve -
ment.
Going forward, we see three main areas 
of improvement for the neo-  socioanalytic 
model. First, we need to test the mecha -
nisms of both continuity and change in 
longitudinal research. What we currently 
think of as mechanisms may not actually 
be mechanisms, resulting in changes to and 
greater parsimony of the model. Second, the 
focus of the neo-  socioanalytic model (and 
most other related frameworks) is person -
ality development in adulthood. There is a 