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Bystander Effect — 3 Comments

  1. Bystander effect. Someone probably already sent you stuff, but …

    Psychol Bull. 2011 May 2. [Epub ahead of print]
    The bystander-effect: A meta-analytic review on bystander intervention
    in dangerous and non-dangerous emergencies.
    Fischer P, Krueger JI, Greitemeyer T, Vogrincic C, Kastenm├╝ller A,
    Frey D, Heene M, Wicher M, Kainbacher M.
    Research on bystander intervention has produced a great number of
    studies showing that the presence of other people in a critical
    situation reduces the likelihood that an individual will help. As the
    last systematic review of bystander research was published in 1981 and
    was not a quantitative meta-analysis in the modern sense, the present
    meta-analysis updates the knowledge about the bystander effect and its
    potential moderators. The present work (a) integrates the bystander
    literature from the 1960s to 2010, (b) provides statistical tests of
    potential moderators, and (c) presents new theoretical and empirical
    perspectives on the novel finding of non-negative bystander effects in
    certain dangerous emergencies as well as situations where bystanders
    are a source of physical support for the potentially intervening
    individual. In a fixed effects model, data from over 7,700
    participants and 105 independent effect sizes revealed an overall
    effect size of g = -0.35. The bystander effect was attenuated when
    situations were perceived as dangerous (compared with non-dangerous),
    perpetrators were present (compared with non-present), and the costs
    of intervention were physical (compared with non-physical). This
    pattern of findings is consistent with the arousal-cost-reward model,
    which proposes that dangerous emergencies are recognized faster and
    more clearly as real emergencies, thereby inducing higher levels of
    arousal and hence more helping. We also identified situations where
    bystanders provide welcome physical support for the potentially
    intervening individual and thus reduce the bystander effect, such as
    when the bystanders were exclusively male, when they were naive rather
    than passive confederates or only virtually present persons, and when
    the bystanders were not strangers. (PsycINFO Database Record (c) 2011
    APA, all rights reserved).

    PMID: 21534650 [PubMed – as supplied by publisher]

    Br J Soc Psychol. 2010 Dec;49(Pt 4):785-802. Epub 2010 Feb 1.
    The implicit identity effect: identity primes, group size, and helping.
    Levine M, Cassidy C, Jentzsch I.
    Department of Psychology, Lancaster University, UK. m.levine@lancaster.ac.uk
    Three studies consider the implicit bystander effect in the light of
    recent advances in social identity approaches to helping. Drawing on
    the social identity model of deindividuation effects we argue that the
    implicit bystander effect is shaped not by the number of others
    imagined, but by who those others are imagined to be. Studies 1 and 2
    demonstrate that, when group membership is primed, increasing group
    size can facilitate helping in line with the norms and values of the
    group. Study 3 explores mediation processes in group level helping. As
    group size increases, female participants react faster to words
    associated with communalism when others are imagined as women rather
    than strangers. The paper demonstrates that group size and helping
    behaviour is qualified by an implicit identity effect.

    PMID: 20122306 [PubMed – indexed for MEDLINE]

    J Pers Soc Psychol. 2008 Dec;95(6):1429-39.
    The responsive bystander: how social group membership and group size
    can encourage as well as inhibit bystander intervention.
    Levine M, Crowther S.
    Department of Psychology, Lancaster University, Lancaster, United
    Kingdom. m.levine@lancaster.ac.uk
    Four experiments explored the interaction of group size, social
    categorization, and bystander behavior. In Study 1, increasing group
    size inhibited intervention in a street violence scenario when
    bystanders were strangers but encouraged intervention when bystanders
    were friends. Study 2 replicated and extended these findings to social
    category members. When gender identity was salient, group size
    encouraged intervention when bystanders and victim shared social
    category membership. In addition, group size interacted with
    context-specific norms that both inhibit and encourage helping. Study
    3 used physical co-presence and gender identities to examine these
    social category effects. Increasing group size of women produced
    greater helping of a female victim, but increasing group size of men
    did not. Additionally, increasing numbers of out-group bystanders
    resulted in less intervention from women but more intervention from
    men. Study 4 replicated these findings with a measure of real-life
    helping behavior. Taken together, the findings indicate that the
    bystander effect is not a generic consequence of increasing group
    size. When bystanders share group-level psychological relationships,
    group size can encourage as well as inhibit helping.

    PMID: 19025293 [PubMed – indexed for MEDLINE]

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