While there may not be much difference in a practical sense between sole custody and joint legal custody, there is a hell of a difference between sole physical custody and joint physical custody!
What follows are papers published on joint custody, primarily theses because that is usually the best source. I have started with 1980 as a starting date arbitrarily because that limits it to about 30 titles.
Please note in considering research in this area that it is important to place more trust on comparative studies than descriptive studies. There are a lot of subjective conclusions made and comparison studies, i.e. comparing same-age, same-sex children from different environments is less subjective than just looking at children from one environment and trying to come to conclusions from interviews.
The main research papers discussing custody issues:
A. Luepnitz. Maternal, paternal and joint custody: A study of families after divorce. Doctoral thesis 1980. State University of New York at Buffalo. UMI No. 80-27618. Luepnitz studied single parent custody and joint custody. Most single parent children were dissatisfied with the amount of visitation they had, whereas the children of joint custody arrangements seemed reasonably happy with their exposure to both their parents. The quality of the parent-child relationship was determined to be better for joint custody. (The ncp-child relationship is described as more like an aunt or uncle - child relationship.)
S.A. Nunan. Joint custody versus single custody effects on child development. Doctoral thesis 1980. California School of Professional Psychology, Berkeley, UMI No. 81-10142 Nunan compared 20 joint custody children (ages 7-11) with 20 age-matched children in sole maternal custody. All families were at least two years after separation or divorce. Joint custody children were found to have higher ego strengths, superego strengths and self-esteem than the single custody children. The joint custody children were also found to be less excitable and less impatient than their sole custody counterparts. For children under four at the time of separation the differences were very small.
B. Welsh-Osga. The effects of custody arrangements on children of divorce. Doctoral thesis 1981. University of South Dakota. UMI No. 82-6914. Welsh-Osga compared children in intact families with joint custody and single custody families. Age range 4 1/2 to 10 years old. Children from joint custody were found to be more satisfied with the time spent with both parents. Parents in joint custody were found to be more involved with their children. (Joint custody parents found to be less overburdened by parenting responsibilities than sole custody parents.) Children from all four groups (intact families, sole maternal, sole paternal, joint custody) were found to be equally well adjusted by their various standardized measures.
D.B. Cowan. Mother Custody versus Joint Custody: Children`s parental Relationship and Adjustment. Doctoral Thesis 1982. University of Washington. UMI No. 82-18213. Cowan compared 20 joint custody and 20 sole (maternal) custody families. Children in joint physical custody were rated as better adjusted by their mothers compared with children of sole custody mothers. The children`s perceptions in sole custody situations correlated with the amount of time spent with their father! The more time children from sole maternal custody spent with their fathers, the more accepting BOTH parents were perceived to be, and the more well-adjusted were the children.
E.G. Pojman. Emotional Adjustment of Boys in Sole and Joint Custody compared with Adjustment of Boys in Happy and Unhappy Marriages. Doctoral thesis 1982. California Graduate Institute. UMI No. ? Pojman compared children in the age range 5 to 13 years old. Boys in joint custody were significantly better adjusted than boys in sole maternal custody. Comparing boys in all groups, boys in joint custody compared very similarly to boys from happy families.
E.B. Karp. Children`s adjustment in joint and single custody: An Empirical Study. Doctoral thesis 1982. California school of professional psychology, Berkeley. UMI No. 83-6977. Age range of children 5 to 12 years, studying early period of separation or divorce. Boys and girls in sole custody situation had more negative involvement with their parents than in joint custody situation. There was in increase reported in sibling rivalry reported for sole custody children when visiting their father (ncp). Girls in joint custody reported to have significantly higher self-esteem than girls in sole custody.
D.A. Luepnitz. Child Custody: A Study of Families after Divorce. Lexington Books 1982. A summary of the thesis in book form.
J.A. Livingston. Children after Divorce: A Psychosocial analysis of the effects of custody on self esteem. Doctoral thesis 1983. University of Vermont. UMI No. 83-26981. Comparative study of children in mother sole custody, father sole custody, joint custody with mother primary, joint custody with father primary. Children in joint custody situations were found to be better adjusted than children in sole custody situations.
L.P. Noonan. Effects of long-tern conflict on personality functioning of children of divorce. Doctoral thesis 1984. The Wright Institute Graduate School of Psychology, Berkeley. UMI No. 84-17931. Long-term effects were studied in joint custody, sole maternal custody and intact families. Children in joint custody families were found to be more active than in sole custody families or intact families. In low conflict situations children did better (demonstrated less withdrawal) than in either sole custody or intact families.
V. Shiller. Joint and Maternal Custody: The outcome for boys aged 6-11 and their parents. Doctoral thesis 1984. University of Delaware. UMI No. 85-11219. The thesis compares 20 boys in joint custody with 20 matched boys in sole maternal custody. A number of tests were used. Boys from a joint custody environment were found to be better adjusted than boys from a sole custody environment.
Joint Custody and Shared Parenting. (Collection of Papers) Published by Bureau of National Affairs, Association of Family and Conciliation Courts. Ed. Jay Folberg. 1984
M.R. Patrician. The effects of legal child-custody status on persuasion strategy choices and communication goals of fathers. Doctoral Thesis 1984. University of San Francisco. UMI No. 85-14995. 90 fathers were questioned regarding how unequal recognition of parental rights might encourage conflict. Joint legal custody was found to encourage parental cooperation and dis-courage self-interest. Sole custody in both custodial AND non-custodial status encouraged punishment-oriented persuasion strategies. Unequal custody power was perceived as inhibiting parental cooperation by BOTH parents.
G.M. Bredefeld. Joint Custody and Remarriage: its effects on marital adjustment and children. Doctoral Thesis. California School of Professional Psychology, Fresno. UMI No. 85-10926 Both sole and joint custody children adjusted well to the remarriage of their parent; no significant difference found between the groups. The parents of joint custody situations, however, expressed more satisfaction with their children and indicated that they appreciated the time alone with their new spouse. Sole custody children also reported seeing their father less often after remarriage of the mother; this did not happen in joint custody situations.
B.H. Granite. An investigation of the relationships among self-concept, parental behaviors, and the adjustment of children in different living arrangements following a marital separation and/or divorce. Doctoral thesis 1985. University of Pennsylvania, Philadelphia. UMI No. 85-23424. Parents in sole custodial homes (both maternal and paternal) were perceived as using psychological pressure techniques to control children. e.g. inducing guilt. However, in joint custody homes, the perception of the children was that such techniques were seldom used. No difference in self-concept was detectable among the different homes. Children`s ages 9-12 years. 15 joint, 15 maternal sole, 15 paternal sole.
S. Handley. The experience of the child in sole and joint custody. Doctoral thesis 1985. California Graduate School of Marriage and Family Therapy. Joint custody children more satisfied than sole custody children.
S.M.H.Hanson. Healthy single parent families. Family Relations v.35, p.125-132, 1985. 21 joint custody and 21 sole custody families compared. Mothers in joint custody found in better mental health. Mothers with sole custody sons had the least amount of social support and mothers with joint custody of sons had the most. Joint custody mothers reported best child-parent problem solving of all.
S. A. Wolchik, S. L. Braver and I.N. Sandler. J. of Clinical Child Psych. Vol. 14, p.5-10, 1985. Self-esteem found higher in children of joint custody. Children in joint custody report significantly more positive experiences than children of sole maternal custody.
P. M. Raines. (Misplaced reference) Paper describes a survey of 1,200+ children whose parents are in process of divorcing. Children wishing to live with both parents given as a function of age: under age 8, 90%; age 8 - 10, 76%, age 10 - 12, 44%. 1985 paper.
J. Pearson and N. Thoennes. The Judges Journal, Winter, 1986. Will this Divorced Woman Receive Support? Your Custody Decision may determine the Answer. Child support compared among sole custody and joint custody. Joint custody shown to produce much better compliance in child support payments to the mother.
J.S. Wallerstein and R. McKinnon. Joint Custody and the Preschool Child. Behavioral Sciences and the Law, v.4, p.169-183, 1986. This paper presents joint custody for young children in a negative light, however, it is based on descriptive research not comparative research, having no control or comparison group.
E.E. Maccoby, R.H. Mnookin and C.E. Depner. Post-divorce families: Custodial arrangements compared. American Association of Science, Philadelphia. May 1986. Mothers with joint custody were found to be more satisfied, when compared with mothers in sole custody situation.
P. M. Raines. Joint custody and the right to travel: legal and psychological implications. J. of Family Law, v. 24, 625-656, 1986
P. Neubauer. Reciprocal effects of fathering on parent and child. Men Growing Up. (1986)
J. Schaub. Joint Custodu After Divorce: Views and Attitudes of Mental Health Professionals and Writers. Rutgers University, Doctoral Thesis. 1986. No. 86-14559
V. Shiller. Joint versus maternal families with latency age boys: Parent characteristics and child adjustment. American Journal of Orthopsychiatry, v. 56, p. 486-9, 1986. Interviews with boys as well as with both parents. Age group 6-11. Found boys from joint custody families better adjusted than comparison group of boys from sole maternal custody families.
M.B. Isaacs, G.H. Leon and M. Kline. When is a parent out of the picture? Different custody, different perceptions. Family Process, v.26, p.101-110, 1987. This study compares children from five groups: joint physical custody, joint-legal maternal-physical, joint-legal paternal-physical, sole maternal and sole paternal custody. On their measurement of how children perceive the importance of family members, sole custody children were three times mores likely to omit one parent than joint custody situations.
F.S. Williams. Child Custody and Parental Cooperation. American Bar Assn, Family Law, August 1987. Williams studied high-conflict, high-risk situations. He found that children in sole custody (typically but not exclusively maternal) much more likely to be subject to parental kidnapping and/or physical harm. He found that high-conflict families do better and are more likely to learn cooperative behavior when given highly detailed orders from the judge.
CRC Report: R-103A. Synopses of Sole and Joint Custody Studies. Shows that the preponderance of research supports the presumption that joint custody is in the best interests of children. 1987.
A GOOD REVIEW PAPER: J.B. Kelly. Longer term adjustment in children of divorce: Converging Findings and Implications for Practice. Journal of Family Psychology, v.2, p.112-140, 1988.
M. Zaslow. Sex Differences in children`s response to parental divorce. Paper 1. Research methodology and postdivorce family forms. American J. of Orthopsychiatry. v.58, 355, 1988. Paper 2. Samples, Variables, Ages and Sources. Am. J. Orthopsychiatry, v.59, p118, 1989.
J.S. Wallerstein and S. Blakeslee. Second chances: Men, women and children after divorce. New York,Ticknor and Fields. 1989
M. Kline, J.M. Tschann, J.R. Johnson and J.S. Wallerstein. Children`s adjustment in joint and sole custody families. Developmental Psychology, v. 25, p. 430-435, 1989. This work finds that in non-conflicted joint and sole custody families there is little measurable difference between a child`s behavior in sole or joint custody. (Strangely, this paper states "Some quantitative studies have found no differences in symptomatology between joint and sole custody children", citing work by Luepnitz and also Wolchik, Braver and Sandler. However, Luepnitz pointed out that joint custody children retain a more normal parent-child relationship than sole custody children, Wolchik et al found that joint custody children have significantly more positive experiences and higher self-esteem than sole custody counter-parts!)
Lehrman paper Study of 90 children, equally divided between joint physical, joint-legal maternal, and sole maternal custody. Sole custody children shown to have greater self-hate and perceived more rejection from their fathers. Joint physical and joint legal custody children suffered fewer emotional problems than sole custody children. 1990 paper, have mis-placed reference.
L.M.C. Bisnaire, P.Firestone and D. Rynard. Factors associated with academic achievement in children following parent separation. American J. of Orthopsychiatry. v.60(1), p.67-76, 1990 Visitation found to be a most significant factor in enabling children to maintain pre-divorce academic standards.
J. Pearson and N. Thoennes. Custody after divorce: Demographic and attitudinal patterns. American Journal of Orthopsychiatry, v.60(2), p. 233-249, 1990. Regular visitation shown to be significant in a number of factors explaining positive adjustment patterns.
R.A. Warshak. The Custody Revolution. 1992.
D. Popenoe, Associate Dean for Social and Behavioral Sciences of Rutgers University, co-chairman of the Council on Families in America. "The Controversial Truth: Two-parent Families are Better." Published in Speak out for Children, v.8 Winter 1992-3.
The Best Parent is Both Parents, D.L. Levy, Hampton Roads Publishing Co., Norfolk, Virginia. 1 (800) 677-8707. 1993.
Address for obtaining theses:
University Microfilms International, 300 North Zeeb Rd, Ann Arbor, MI 48106.