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Forget the Cinderella effect: stepparents are just as likely to kill their biological children as their stepchildren

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By Tim O’Mahony Operations Manager at Kexue Communications, www.kexuecommunications.com
Researchers have known since the early 1970s that children in stepfamilies are at greater risk of child abuse and murder (Fergusson, Fleming & O’Neill, 1972). A team of Swedish researchers has found that parents in stepfamilies are equally likely to kill their biological children as they are to kill their stepchildren. Their findings are published in the journal Current Zoology (Online First).

Evolutionary reasons such as a lack of genetic relatedness and kin selection have previously been used to explain the higher rates of child abuse and homicide observed in stepfamilies (Daly & Wilson, 1988). The research team from Stockholm University and Mid Sweden University investigated whether an evolutionary explanation sufficiently explained this higher prevalence.

The research team analyzed Statistics Sweden records of parental child homicides in Sweden for the period 1965–2009. They included data from two biparental family types in their study: families with two genetic parents and stepfamilies. The group also analyzed the proportion of stepfamilies and families with two genetic parents in the general population for 1987, the midpoint of the study, to determine whether children in stepfamilies were statistically more likely to be murdered.

Dr. Temrin’s team used contingency tables to compare the observed frequencies of parents from the two family types committing child homicide with the frequencies of parents in the two family types in the general population. They found that on average there are 3.2 perpetrators per million parents for stepfamilies, and 1.9 per million parents for families with two genetic parents.

The team also investigated perpetrators in stepfamilies specifically, by finding the ratio of biological parent and stepparent child homicide perpetrators in stepfamilies and comparing it to an expected 1:1 ratio using a Chi-square test.

There were 152 perpetrators of parental child homicide in the two family groups used over the 45 year study period: 125 perpetrators were in families with two genetic parents and 27 were in stepfamilies. Of the 27 stepfamily murderers, 13 killed their genetic children, 13 murdered their stepchildren, and 1 perpetrator killed both. This means that the risk of a stepparent or a genetic parent in a stepfamily murdering a child is not significantly different from a 1:1 ratio (Chi-square = 0, p > 0.99).

“Our study suggests that the risk of being killed is not associated primarily with the non-genetic relation stepparent and stepchild but rather by living in a stepfamily,” said the paper’s lead author, Dr. Hans Temrin from Stockholm University.

Data on the criminal record of all Swedish parents in both genetic parent families and stepfamiles was also taken from the The Swedish National Council for Crime Prevention dataset for the midpoint of the study, 1987.

Dr. Temrin’s team found that rates of crime across Sweden were higher for adults in stepfamilies than in biparental families, with general crime 1.5 times higher (28.2% vs. 17.8%), and violent crime twice is high (4.4% vs. 1.9%). These findings agree with previous studies that found that there is a higher incidence of unemployment, psychiatric problems and anti-social behaviors for parents in stepfamilies than parents in families with both genetic parents (Belsky, 1993; Turner, Finkelhor & Ormrod, 2007).

“The Cinderella effect – the observation that adults are more likely to kill their stepchildren than their biological children – has long been a staple of evolutionary psychology-informed homicide research, and this study suggests that this explanation is likely too simple,” said Dr Damon Muller from the National Centre for Epidemiology and Population Health at the Australian National University.

Dr. Temrin explains that “most parental child homicides are not caused by conflicts with the child but rather by problems that parents have.”

“Giving help to people with psychiatric problems and to families with problems in my opinion is the only way to decrease child maltreatment and the risk of children being killed.”

The research team hopes to replicate their study in other countries to investigate whether their observations hold.

References

Belsky J, 1993. Etiology of child maltreatment: A developmental-ecological analysis. Psychological Bulletin 114: 413-434.

Daly M, Wilson M, 1988. Homicide. New York: Aldine de Gruyter.

Fergusson DM, Fleming J, O’Neill DP, 1972. Child abuse in New Zealand. Wellington, New Zealand: A. R. Shearer, Government Printer.

Turner HA, Finkelhor D, Ormrod R, 2007. Family structure variations in patterns and
predictors of child victimization. American Journal of Orthopsychiatry 77: 282-295.

Questions about “The Self”

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In recent times there has been a lot of discussion with regard to social psychology constructs such as self-esteem, self-determination and self-affirmation. Due to rapidly changing societies and new insights into cognitive processes of memory formation some old theories of self-psychology have recently been challenged. For example Heine, Lehman, Markus and Kitayama (1999) postulated that self-esteem, conceptualized as positive self-regard, is not a universal value and should be replaced by the concept of self-enhancement. However, all those theories are closely connected to the concept of self, which in itself still remains unclear. Since there are many different interpretation of the self, many discussions end in despair, each side holding on to their specific conceptualization of the self, which are not interchangeable. But can there be any definition that fits them all? Does “talking about myself” and “exercising control over myself” relate to the same objects?

Terms such as self-esteem suggest that there is stability of that process on the influence of behavior. However people can switch between different roles (selves?) with relative ease. Reinders et al. (2003) showed that in patients with Multiple Personality Disorder, there are specific cerebral blood flow patterns mainly in the medial prefrontal cortex and the posterior associative cortices that can produce different senses of self. It is parsimonious to assume that the same process also mediates the different senses of self in healthy persons, however to a lesser extend in the sense that every self is aware of its coexistence within one person. Different selves have been postulated, such as the social self, the future self, the past self, the material self, the spiritual self… But do constructs such as self-esteem relate to all the selves in the same way or do they apply differently to different selves? Are there processes that extend through all the possible selves? Should we specify a specific self when looking at a process such as self-esteem?

People who have grown up in different cultures report that their self-concept differs in relation to the environment, as shown by Markus and Kitayama (1991). Chinese Canadians completed different measures with regard to the self, such as a measurement of independent, interdependent self-construal. When the test was conducted in a European setting (English researcher, English questions) their self-construct was predominantly independent. However if the setting (environment) was different (Chinese researcher, test in Chinese) their self-construct was more interdependent. Ross, Xun and Wilson (2002) replicated those findings and extended the method to other self-related constructs. They conclude that identities of bicultural persons may be stored in separate knowledge structures, which can be activated by the associated language.

At that point let’s take a look at different theories about the self. Descartes thought that the self was some entity that existed outside of the material body. William James defined the self as an object of knowledge consisting of whatever the individual views as belonging to himself (Epstein, 1973). George Mead noticed that the self-concept arises in social interaction as product of the individuals concerns of how others will react. Rogers saw the self as an organized fluid, but conceptual pattern of perceptions of characteristics and relationships of the ‘I’ or the ‘Me’, together with values attached to these concepts. Allport used the term proprium instead of self to stress the aspects of the individual that he or she regards of central importance and which contribute to a sense of inward unity. Furthermore the self has been described as a self-theory (Epstein, 1973),and as a cognitive knowledge structure. Sarbin remarked that behavior is organized around cognitive structures. Recently neurobiological pathways (especially the CMS, cortical midline structures) have been found to play an important role in self-referential processes. Those processes, distinguishing stimuli related to one’s own self from those that are not relevant to one’s self, might be the computing basis for the different kinds of self-concepts that have been observed.

I believe that the concept of self entails different cognitive processes, which should be looked at in the most abstract way still meaningful. Arguing from a philosophical, mechanical perspective I believe that having cognitive processes that assign a self / non-self marker to different knowledge objects should be enough to construct a theory of self. I assume that “the self” is a cognitive object that is constructed on-line, depending on the task and environment at hand. The content of those temporary self-representations is drawn for the knowledge that has been marked by the reflexive process as possessing the self-attribute. Those knowledge objects frequently used for the construction of the self should over time become chronically accessible. Such a definition of self would allow many degrees of freedom and would fit many definitions of the self previously given. Thus I propose that whenever “the self” is involved, it is necessary to specify which cognitive processes are suggested to be involved. I also propose that the environment for which the theory or hypothesis is formulated should be explicitly described. Ultimately it might be better to talk about reflexive processes instead of the self.

References

Epstein, S. (1973). The self-concept revisited. American Psychologist, 28, 404-414.
Heine, S. J., Lehman, D. R., Markus, H. R. & Kitayama, S. (1999). Is there a universal need for positive self-regard? Psychological Review, 106, 766-794.
Markus, H. R. & Kitayama, S. (1991). Culture and the self: implications for cognition, emotion, and motivation. Psychological Review, (98), 224-253.
Reinders, A. A. T. S., Nijenhuis, E. R. S., Paans, A. M. J., Korf, J., Willemsen, A. T. M., & Boer, J. A. (2003). One brain, two selves. NeuroImage, (20), 2119-2125.
Ross, M., Xun, W. Q. E., & Wilson, A. E. (2002). Language and the bicultural self. Personality and Social Psychology Bulletin, 28, 1040-1050.

Written by Martin Glanert

September 22, 2008 at 9:54 pm