A general factor of intelligence fails to account for changes in tests’ scores after cognitive practice: A longitudinal multi-group latent-variable study Eduardo Estrada a , Emilio Ferrer b , Francisco J. Abad a , Francisco J. Román a , Roberto Colom a, ⁎ a Facultad de Psicología, Universidad Autónoma de Madrid, Spain b University of California at Davis, USA article info abstract Article history: Received 23 December 2014 Received in revised form 4 February 2015 Accepted 20 February 2015 Available online xxxx As a general rule, the repeated administration of tests measuring a given cognitive ability in the same participants reveals increased scores. This brings to life the well-known practice effect and it must be taken into account in research aimed at the proper assessment of changes after the completion of cognitive training programs. Here we focus in one specific research question: Are changes in test scores accounted for by the tapped underlying cognitive construct/factor? The evaluation of the factor of interest by several measures is required for that purpose. 477 university students completed twice a battery of four heterogeneous standardized intelligence tests within a time lapse of four weeks. Between the pre-test and the post-test sessions, some participants completed eighteen practice sessions based on memory span tasks, other participants completed eighteen practice sessions based on processing speed tasks, and a third group of participants did nothing between testing sessions. The three groups showed remarkable changes in test scores from the pre-test to the post-test intelligence session. However, results from multi-group longitudinal latent variable analyses revealed that the identified latent factor tapped by the specific intelligence measures fails to account for the observed changes. © 2015 Elsevier Inc. All rights reserved. Keywords: General cognitive ability Practice effect Working memory span Processing speed 1. Introduction Practice effects are broadly acknowledged in the cognitive abilities literature (Anastasi, 1934; Colom et al., 2010; Hunt, 2011; Jensen, 1980; Reeve & Lam, 2005). When the same individuals complete the same (or parallel) standardized tests, their scores show remarkable improvements. However, as discussed by Jensen (1998) among others (Colom, Abad, García, & Juan-Espinosa, 2002; Colom, Jung, & Haier, 2006; te Nijenhuis, van Vianen, & van der Flier, 2007), specific measures tap cognitive abilities at three levels: general ability (such as the general factor of intelligence, or g), group abilities (such as verbal or spatial ability), and concrete skills required by the measure (such as vocabulary or mental rotation of 2D objects). Within this general framework, recent research aimed at testing changes after the completion of cognitive training programs has produced heated discussions regarding the nature of the changes observed in the measures administered before and after the training regime (Buschkuehl & Jaeggi, 2010; Conway & Getz, 2010; Haier, 2014; Moody, 2009; Shipstead, Redick, & Engle, 2010, 2012; Tidwell, Dougherty, Chrabaszcz, Thomas, & Mendoza, 2013). The changes may or may not be accounted for by the underlying construct of interest. Thus, for instance, the pioneering work by Jaeggi, Buschkuehl, Jonides, and Perrig (2008) observed changes in fluid intelligence measures after completion of a challenging cognitive training program based on the dual n-back task. This report stimulated a number of investigations aimed at replicating the finding (Buschkuehl, Hernandez-Garcia, Jaeggi, Bernard, & Jonides, 2014; Colom et al., Intelligence 50 (2015) 93–99 ⁎ Corresponding author at: Facultad de Psicología, Universidad Autónoma de Madrid, 28049 Madrid, Spain. Tel.: +34 91 497 41 14 (Voice). E-mail address: roberto.colom@uam.es (R. Colom). http://dx.doi.org/10.1016/j.intell.2015.02.004 0160-2896/© 2015 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Intelligence