Short-term Memory and Auditory Processing Disorders: Concurrent Validity and Clinical Diagnostic Markers

Auditory processing disorders (APDs) are of interest to educators and clinicians, as they impact school functioning. Little work has been completed to demonstrate how children with APDs perform on clinical tests. In a series of studies, standard clinical (psychometric) tests from the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) were used to establish concurrent validity between tests of short-term auditory memory and two frequently used tests of auditory processing (Dichotic Digits and Frequency Patterns). The diagnostic utility of the short-term memory tests was also explored. In a matched sample, Digit Span forward predicted diagnosis of APD (sensitivity = .81, specificity = .78). Furthermore, within-subjects analyses for the clinical group found that Digit Span forward scores were significantly lower than those for the other psychometric tests (p values < .001 for Digit Span backward, Letter Span nonrhyming and rhyming scores). Although APD is a low base-rate condition, the utility of these tests as a potential screener or marker for APDs was demonstrated. The need for further studies was endorsed. M A E R L E N D E R , P S Y C H O L O G Y I N T H E S C H O O L S 4 7 (2 0 1 0 ) 2 Auditory processing disorders (APDs) are deficits in the information processing of audible signals not attributed to impaired peripheral hearing sensitivity or intellectual impairment. These deficits disrupt the continuous auditory processing of acoustic, phonetic, and linguistic information and affect information processing from sound reception to discourse understanding (Jerger & Musiek, 2000). An APD may be manifest as a deficit in sound localization, discrimination, pattern recognition, temporal processing, and performance deficits when the auditory signal is degraded or embedded in competing acoustic signals. These deficits have electrophysiological as well as behavioral correlates (Bamiou, Musiek, & Luxon, 2001). Prevalence estimates of APDs put the rate of this disorder at 2%–3% of all children, with boys having the disorder twice as often as girls (Chermak & Musiek, 1997). Some of the symptoms associated with APDs include being easily distracted by loud or sudden noises, having improved behavior and performance in quieter settings, having difficulty following directions and conversations, frequently saying “huh” or “what,” having difficulty listening when there is background noise, and having poor auditory attention. The diagnosis of APDs has become a frequent occurrence in schools, although APDs are not recognized in medical diagnostic nomenclature. Current identification practice is based on audiological (“audiometric”) testing. This testing is currently done only in appropriately equipped laboratories. Behavioral testing relies on psychophysical paradigms in which stimuli are presented in varying frequencies, intensities, et cetera to establish the level at which the subject can accurately respond. An issue for clinicians and psychologists is how these APDs relate to better known psychological constructs. Few studies have looked at relationships between APD test scores and scores on standard tests and psychometric tests. Furthermore, the behavioral phenotype described by audiometric tests is unique to their profession. Thus, the purpose of this study was to relate those phenotypic characteristics to constructs with which psychologists are familiar. Watson and Miller (1993) found that performance on the auditory span tasks was modestly related to speech perception and nonsense word decoding on a staggered spondaic word test (r = .22 to .39). Participants were reading disabled and non–reading-disabled college students. Parkinson (1974) found strong relationships between dichotic listening and “digit memory” in college students, suggesting that short-term auditory memory and central auditory processes are related. In a series of retrospective analyses, Maerlender, Wallis, & Isquith (2004) demonstrated that the Digit Span subtest of the Wechsler Intelligence Scale for Children, Third Edition (WISC-III) was strongly related to a dichotic listening test, considered the most robust measure of APD (Musiek, Gollegly, & Ross, 1985). Furthermore, the forward span element of this subtest was the most robust indicator of APD diagnosis. Two recent studies of APD and neuropsychological tests in children with AttentionDeficit/Hyperactivity Disorder (ADHD) have found some relationships among psychometric tests. In the first, Riccio, Cohen, Garrison, and Smith (2005) studied 36 children with ADHD and administered a series of auditory and neuropsychological tests to identify relationships among audiometric tests and neuropsychological tests. Correlational analysis revealed only one significant correlation: between the right ear score of the Staggered Spondaic Word (SSW) test and a memory for sentences test (Clinical Evaluation of Language Fundamentals, 3rd ed., Sentence Repetition). They concluded that auditory M A E R L E N D E R , P S Y C H O L O G Y I N T H E S C H O O L S 4 7 (2 0 1 0 ) 3 measures tap some element of auditory memory and that APD and ADHD may be overlapping but independent disorders. In a clinical sample of children with APD matched on age and IQ score with WISC-IV clinical ADHD cases from the standardization sample, Maerlender (2006) compared the Digit Span forward (DSF) and Letter Span (rhyming and nonrhyming) scores. There were significant differences between groups on DSF and Letter Span nonrhyming scores, with DSF accounting for the most variance and providing the best discrimination between groups (Maerlender, 2006). Thus, in support of Riccio and colleagues (2005), the data provided evidence that APD was likely an independent diagnostic construct from ADHD, although significant comorbidity was also evident. The studies reported here sought to answer the following questions: (a) Can psychometric tests be used to reliably identify children with APD? and (b) Was there convergent validity between the psychometric tests and the audiometric tests? The first question was addressed using two different comparison groups (Study 1 and Study 2). The second question was addressed in Study 1.