The Abel Assessment for Sexual Interest (AASI, versions 1, 2 and 3) was developed with the hope that it could measure sexual attraction without being as invasive as the plethysmograph. The core component of the AASI is a measure of viewing time (VT), determined by the amount of time slides are retained on a computer screen by the subject being tested. In addition to the VT measure, the AASI includes a measure of self – reported sexual attraction to the VT stimuli, a self-report questionnaire and a client data form filled out by the therapist.
The first version of the AASI was the Abel Screen, published in 1994. It was designed to screen males with no known history of sexual offenses for pedophilic interests. This version eventually included a probability value that an alleged offender was a child molester. The most recent version (AASI-3) includes questionnaire items on Internet porn use and experience of sexual trauma.
Sachenmaier and Gress (2009) provide an important critique of the AASI-2.
“VT methods of measuring sexual interest have held promise for more than a half century, yet the achievement of good, stable psychometric qualities remains elusive. This is partially due to lack of published psychometric information and the confidential and proprietary nature of the AASI. . . There is a substantial amount of research still required, however, especially on the AASI to substantiate its use. First, researchers and clinicians require peer-reviewed published information on the AASI psychometric properties. This permits proper evaluation of the AASI and comparison between AASI studies and studies utilizing other VT methods. Second, there has been little to no informative research evaluating the AASI on populations exhibiting exhibitionism, frottage, voyeurism, sadism against males and females and rapists. There are scales in the AASI that assess these areas but unfortunately, there does not appear to be an evaluation of the full AASI (all self-report scales plus all pace that scales using the full set of stimulus materials) published in peer-reviewed journals.
Third, an area that requires immediate attention is the reliability and predictability of this measure’s scoring procedures. For example, Abel et.al. (2004) used raw scores (seconds) to ‘increase reliability and predictive ability’ that suggest that the raw score means may be more reliable and predictive than the Z score transformation (p .269). Unfortunately, the latter is what Abel Screen Incorporated provides clinicians to use in practice. Although the results of the analysis utilizing raw scores were significant, they were mediocre in strength . . . Indicating that a discussion of the AASI’s (and VT in general) clinical significance vs. statistical significance is warranted. Finally, research is required to determine the fact, if any, of a client’s knowledge on the purpose and method of the AASI. This is important for all psychometric measures utilized in forensic settings, as the consequences for alleged and known sexual offenders and civil and criminal context can be substantial. Due to this increased personal risk for the client, if he or she knows that they may undergo the AASI assessment (or other psychological measures) they may attempt to learn about the test by searching online.
A search for ‘Abel assessment’ via a popular search engine (e.g. Google) provide a variety of informative websites, including a link to Innocent Dads, which provides a detailed description of how the Abel Assessment measures VT. The more persistent web searcher will also find a New York Times article (Berger, 2005) explaining that the AASI measures erotic preference by the amount of time a person looks at the different slides, not the self-reporting skills sexual attraction. The situation is not the fault of Abel Screen Incorporated, but it is a reality they must live and deal with.
If the accuracy of a test depends upon people’s naïveté, and at this time VT measures appear to do just that, authors of these tools are ethically obligated to provide clinicians information on the effect of non-naïve clients. Abel Screening Incorporated has begun this process by including instructions that alert clinicians to the fact that VT may not accurately reflect a person’s sexual interest pattern: “The integrity of the AASI-2 is dependent on the client’s ability to follow instructions, have reasonable acuity to see the images and not be influenced by auditory or visual hallucinations or brain damage’ (http://abelscreen.com/products, retrieved 12 June, 2007).
Cautions when using the AASI
Much of the integral psychometric information necessary for proper evaluation and interpretation of any psychological instrument is lacking in many of the published studies on the AASI. This includes descriptive numbers (instead of verbal descriptions alone) such as means, standard deviations, correlations and significance levels. The presentation of effect sizes would also greatly improve a reader’s ability to evaluate the significance of research on the AASI. Therefore, until the authors complete the task of publishing this information, we suggest clinicians to be cautious when using and interpreting all components of the AASI. In addition, when administering this tool to special populations or in specific contexts that have not received a thorough psychometric evaluation, such as those described above, the clinician should do so with extreme caution and state the circumstances in any report of the measure’s results.
Another area of concern is the clinical application of the AASI probability values (Abel et al., 2001). Importantly, the probability value should not be used due to the substantial number of false positives and false negatives, lack of cross validation, and other research weaknesses. In addition, there is the inherent potential for committing the error of reversing conditional probabilities. For example, a group of known sexual offenders can be studied and a list made of their most common characteristics, but to take this list of common characteristics and apply it to a non-offending male and use the degree to which that person has these characteristics as a probability that he is a sexual offender demonstrates flawed reasoning. To say, ‘If you are a known sexual offender of boy children, we can look at characteristics a, b, and c’ is not the same as saying, ‘If you have characteristics a, b, and c, you are probably a sex offender of boys’.
Although Abel et al. (2001) cautioned against using either AASI VT or probability values in litigious context, this has not been heeded (see, e.g. United States v. White Horse, 2003; Ready v. Commonwealth of Massachusetts, 2002); consequently, we recommend that use in litigious context should be clearly forbidden by the test manufacturer and so stated on reports. Similarly, AASI users should be aware that the lack of published research, lack of independent cross validation and replication studies and lack of adequate statistical reliability and validity data make the AASI vulnerable to attack under judicial standards for admissibility of expert witness evidence.”
(Pages 53-55 in Sachenmaier, S. and Gress, C. The Abel assessment for sexual interests -2: A critical review. Chapter in Thorton & Laws, Cognitive approaches to the assessment of sexual interest in sexual offenders. John Wiley & Sons, Malden, MA, [2009]).
Sachenmaier and Gress (2009) also offer cautions regarding special populations.
Adolescents
Abel et al. cautioned that the AASI should not be used to identify adolescent males who are accused of child molestation but are denying it, and VT alone should not be used as a classification tool. Abel et al. Suggested that the AASI might best be used to identify high-risk offenders among known adolescent child molesters to help decide who cannot be safely treated in the community. Although this appears to be a reasonable conclusion, recall that ipsative scores such as those used by the AASI do not allow for inner-individual comparisons. Additionally, while a method with a receiver operator characteristic of 0.64 does offer predictive accuracy above that of chance, it is clinically poor result and therefore not an appropriate foundation upon which to base decisions regarding a person’s confinement. A risk assessment should be based on a larger body of test and other data and use methods designed specifically for risks management.” (p.49)
Child Custody
“The summary reports issued by Abel Screen, Inc. indicate that the AASI probability value should not be used in disputed child custody cases. The warning states: ‘You should be aware that child custody dispute cases violate some of the assumptions on which the Denier – Dissimulator probability model is based, and therefore, it should not be used in these situations.’” (p.49-50)
Intellectually Disabled
“Research has used participants were able to read the AASI questionnaire without assistance. Those whose intellectual disability prevents them from doing so should not be tested with the AASI. Abel Screening Incorporated offers for sale the Abel – Blasingame Assessment System for individuals with intellectual disabilities. It appears that the main differences are simplified instructions and a simplified questionnaire that is read to the client. Product information does not mention differences among slide sets. We can find no published research using the Abel – Blasingame Assessment System. Blasingame reported that he is gathering data (personal communication, 9 September 2007), but has not yet received permission from Abel Screening Incorporated to share preliminary results, as data are owned by Abel Screening Incorporated. Publication of this research could be an important advance in the field.” (p.50)
Females
“Abel Screen Incorporated has a questionnaire for female children and female adults. (Abel et al., 2004): however, no researches been reported using female participants with the AASI.” (p.50)
Minority Races
“The AASI includes African American slide stimuli that are to be used with that population. The vast majority of the participants in the research have been Caucasian. The AASI questionnaire is offered in Spanish and French, in addition to English (Abel et al., 2004). There is no published research using substantial numbers of participants from these minorities.” (p.50)
Sadism/Masochism
“The AASI includes stimuli designed to identify sexual interest in sadism against females and sadism against males. The ipsative scores reflected by the AASI bar chart our score differently from the age and gender categories, in that the sadism against female score must succeed the adult female score by full standard deviation and likewise for males, in order for further inquiry to be made of the participant. There is no report of research to support the use of these scores. Abel Screen Incorporated currently advises AASI-2 users not to report the sadism scores. Additionally, Letourneau (2002) did not support the use of the AASI with rapist.” (p.50)
Incest Offenders
“It is commonly accepted that incest offenders are less likely to show sexual interest in children (Abel et al., 2001) then our other child sexual offenders. Abel et al. (2001) excluded incest offenders from the two groups of admitting sex offenders used to construct the probability models for child molesters. Letourneau (2002) speculated that the non-significant findings for sexual interest in female children may have occurred because many of the child molesters were incest offenders. Abel Screen Incorporated reports of the probability value for denier-dissimulator (formerly liar – denier) may be applied to alleged incest offenders. Abel et al. (2001) do not report how many incest offenders were used in the denier group to construct the model, they can investigation of this claim difficult. AASI’s use in child custody battles where incest is alleged has recently been forbidden by Abel Screening Incorporated; this is stated on the website and on AASI summary reports.” (p.51)
Ready v. Commonwealth of Massachusetts (2005)
Appeals Court affirmed a lower court’s ruling.
“the theories and techniques underlying the AASI have not been sufficiently tested for admissibility in this proceeding. . . For all we know, they and their components could be mathematically based, founded upon indisputable empirical research, or simply the magic of young Harry Potter’s mixing potions at the Hogwarts School of Witchcraft and Wizardry.”
“the AASI’s high error rate, coupled with Dr. Abel’s solution to the error rate, which is to merely ‘lower the cut-off score’ (thereby erroneously labeling non-molesters as molesters), substantially detracts from the petitioner’s contention that the AASI is scientifically sound and sufficiently reliable to assist the trier of fact.”
From www.innocentdads.org:
“. . . but what does it REALLY measure. During the first part of the test, it very simply measures your REACTION TIME for various pictures and how you rate each picture. You will be shown 160 slides of boys, girls, men and women dressed normally, dressed in underwear, dressed with bathing suits and in different situations.”
The New York Times: The Making of a Molester – January 23, 2005
“He was taking the Abel Assessment for Sexual Interest, as all the men do at some point during their treatment. It offers a gauge of erotic preference measured not by the 1 to 7 ratings but by the length of time a man lets his eyes linger on each image.”
Published Research on Abel Assessments
Statistical adequacy of the Abel Assessment for Interest in Paraphilias.
Fischer, Lane and Smith, Gillan
Sexual Abuse: Journal of Research and Treatment, Vol 11(3), Jul, 1999. pp. 195-205.
Abstract:
Reviews the psychometric properties of the Abel Assessment for Interest in Paraphilias (AAIP; G. G. Abel, 1995), with the purpose of examining the research supporting the technical adequacy of the AAIP as it is currently marketed for the assessment of sexual offenders. The data supporting the AAIP’s history, purpose, types of data generated, reliability, validity, and norms are reported, with the conclusion that its use with adults is tenuous at best and its use with adolescents is as yet unsupported. Pragmatic concerns are noted, along with recommendations for further research.
Assessment of juvenile sexual offenders: Reliability and validity of the Abel Assessment for interest in paraphilias.
Gillan Smith & Lane Fischer
Sexual Abuse: A Journal of Research and Treatment. 1999;11(3):207–16.
Abstract:
Empirical tests of the reliability and validity of the Abel Assessment for Interest in Paraphilias (AAIP) as used with juvenile sexual offenders were performed. Test–retest reliability, screening validity, and diagnostic validity were assessed using several analytical approaches. The temporal stability, sensitivity, and specificity of the AAIP as used with adolescents in residential and day treatment were not demonstrated. The results indicate the need for further refinement of the AAIP.
The Importance of Meeting Research Standards: A Reply to Fischer and Smith’s Articles on the Abel Assessment for Sexual Interest
Able, Gene
Sexual Abuse: Journal of Research and Treatment April 1, 2000 12: 155-161
Assessing Sex Offenders
Vladimir Coric, et. al.
Psychiatry (Edgmont). 2005 November; 2(11): 26–29.
Astract:
Visual reaction time, or the amount of viewing time spent looking at a particular image, has been hypothesized as being a nonintrusive method of measuring sexual interest.13–16 Based upon the notion that visual reaction time is an indicator of sustained sexual interest, Dr. Gene Abel and associates developed a commercially available product, the Abel Assessment for Sexual Interest. The Abel Assessment for Sexual Interest consists of both subjective and objective components designed to measure sexual interest by age and gender. The first portion of the Abel Assessment consists of a questionnaire that gathers information regarding the client’s sexual preferences and behaviors, legal history, and self-reported ability to control their sexual behaviors. The questionnaire also contains items that are analyzed to assess whether the client is feigning test results, has cognitive distortions about having sex with children, or fits a statistical profile of individuals (known offenders) who have sexually abused children. The objective measure of the Abel Assessment is performed during the second part of the test. Visual reaction time is measured beyond the client’s awareness while viewing 160 slides (in 22 categories) depicting clothed children, teens, and adults. During this portion of the test, the client is also asked to rate his or her degree of sexual arousal to the visual stimuli. Data obtained from the testing is sent to Abel Screening, Inc. for processing and analysis; a detailed report of the client’s response patterns is then provided to the testing site.
Many sites are increasingly utilizing the Abel Assessment due to its ease of administration and noninvasive method of measuring sexual interest. However, the reliability, validity, and statistical analysis of the data supporting the Abel Assessment have been debated in the literature.17–19 Additionally, the admissibility of the Abel Assessment in the courts remains unclear. Care should be taken not to make improper clinical extrapolations regarding risk assessments, predictions of recidivism, or proving/disproving sexual abuse allegations based solely upon the results of the Abel Assessment. When used as part of a comprehensive psychiatric evaluation, the Abel Assessment may be a useful tool in assessing sexual interest and obtaining a thorough sexual behavior history.
Specialized assessment and treatment of adolescent sex offenders.
Fanniff, Amanda M., Becker, Judith V.m Fanniff, Amanda M.
Aggression and Violent Behavior, Vol 11(3), May-Jun, 2006. pp. 265-282.
Abstract:
The accurate and appropriate assessment and treatment of juvenile sex offenders is necessary for public safety and for the juvenile’s own development. A growing body of literature has reported on specialized assessment instruments and treatment strategies for use with juvenile sex offenders. The current article reviews the evidence regarding the reliability and validity of various assessment instruments and outcome research regarding treatments with this population. With regard to assessment, the authors conclude that the most promising area of specialized assessment is risk assessment. With regard to intervention, the authors argue that despite methodological limitations, research on the treatment of juvenile sex offenders suggests that treatments are successful in creating change. Specifically, cognitive behavioral treatment and mulitsystemic therapy have demonstrated decreased recidivism compared to a control group. Recommendations regarding future research for the area and implications with respect to uniqueness of this population are considered.
Quote:
Another instrument designed to assess sexual interest is the Abel Assessment for sexual interest™ (AASI). This instrument provides a less intrusive alternative to the plethysmograph while still using an objective measure of interest rather than relying on self-report. The AASI measures viewing time to various categories of pictures as a measure of sexual interest. Participants are not aware that viewing time is being measured, making this instrument less likely to be susceptible to dissimulation. One highly critical study investigating its psychometric properties found less than satisfactory results regarding the use of this instrument with juvenile sex offenders (Smith & Fischer, 1999). The average correlation between test and retest across categories was .68, with a range of test–retest correlations from .09 to .96, suggesting that some categories show much greater reliability over time than others. Furthermore, the authors found that using the highest z-score method to label an individual as deviant or non-deviant showed a test–retest correlation of .58. The reliability coefficient for the rule of thirds method of labeling a respondent deviant was .48 (Smith & Fischer, 1999). Assuming that sexual interest should be stable over short periods of time, the lack of adequate test–retest reliability suggests that there is considerable error making results on this instrument unstable.
Smith and Fischer (1999) also reported problematic results of the validity of the AASI. They reported no significant differences on viewing time between a group of sex offenders and a control group of adolescents receiving treatment for problems other than sexual behavior (Smith & Fischer, 1999). Using the rule of thirds method to identify deviant interest, the AASI correctly identified 61% of offenders. Using the highest z-score method, the AASI correctly identified 95% of non-offenders. Unfortunately, the rule of thirds method has an unacceptable false positive rate (42%) and the highest z-score method has an unacceptable false negative rate (90%; Smith & Fischer, 1999). The comparison sample was a treatment group rather than a community sample, which would be ideal as a normative comparison group, limiting the conclusions that can be drawn from this research. Furthermore, Abel (2000) noted that Smith and Fischer (1999) did not ask their control group whether or not they had engaged in any sexually inappropriate behavior, therefore the control group may have included some “offenders,” skewing the results to have a low rate of true negatives and a high rate of false positives. However, the highest true positive rate, which should be unaffected by the nature of the control group, was only 61%. Unfortunately, without significance testing, it is unclear whether or not this hit rate is significantly better than chance.
Smith and Fischer (1999) also failed to find a relationship between victim selection and viewing time, which Abel (2000) explains is the result of not screening for participants with sustained interest in children. Given that not all juveniles who molest children demonstrate deviant sexual interest, it is reasonable to suggest that results would not be significant in a small sample of offenders (81) who do not necessarily each have sustained interest in children. Additional research conducted by the developers of the AASI with a much larger sample (N = 1704) found that juveniles who had molested children looked at slides of children significantly longer than juveniles who had engaged in other types of sexual offenses (Abel et al., 2004). This study also found that among juveniles who had abused children, those who spent more time looking at slides of children had significantly more victims and committed significantly more incidents of inappropriate sexual behavior than those who looked at slides of children for less time. Using Receiver Operating Characteristic (ROC) curve analysis, the area under the curve was too low for the AASI to be used to discriminate between offenders who had molested children and those who had not (Abel et al., 2004). Given the ROC analysis findings in this study and the low true positive rate found by Smith and Fischer (1999), continued research and refinement of the AASI appears necessary. Clinicians who choose to include AASI results in written reports should note the current state of the literature in accordance with the APA Ethical Principles (APA, 2002). Future research should also compare the performance of offenders to a community sample of juveniles. Additionally, as Abel et al. (2004) point out, the currently existing data do not address how juveniles who deny their offenses would perform on the AASI. It would be clinically useful to conduct research examining whether treatment leads to change in response to the AASI and whether such change is related to a reduction in sexual recidivism.
The Abel assessment for sexual interests: Impact of antisocial personality features and pedophilic tendencies on test performance.
Casey, Kelly A., Alliant International U, San Diego, US
Dissertation Abstracts International: Section B: The Sciences and Engineering, Vol 69(2-B), 2008. pp. 1318.
Abstract:
Problem. Diagnoses of Antisocial Personality Disorder and Pedophilia are two significant risk factors for sexual recidivism in child molesters. It is unclear from the existing research, however, whether commonly used measures of sexual interest, such as the Abel Assessment for Sexual Interest (AASI), are capable of detecting high-risk offenders who are not motivated by a Pedophilic interest in children. The current dissertation will attempt to address this limitation by examining the AASI performance of other high-risk child molester subgroups. Method. The archival data of 165 adult male sex offenders, including 107 child molesters and 58 offenders against adults, were analyzed for interactions between participants’ AASI profiles, MCMI-III profiles, Screening Scale for Pedophilic Interest scores, and admitting status. One-way ANOVA analyses were conducted to determine which factors were significantly related to one another. Logistic regression analyses were also performed to determine the classification accuracy of the AASI for each subgroup of child molesters. Results. The child molesters and offenders against adults differed on multiple key demographic and crime-related variables, including their number of sex-offense victims and non-sexual offenses. The MCMI-III profiles of the two offender groups did not differ. On the AASI, however, participants with longer viewing times on the deviant stimuli categories and shorter viewing times for the Adult Female slides were most often classified as a child molester. When the strength of the child molesters’ pedophilic and antisocial tendencies were taken into account, the antisocial child molesters were found to have shorter viewing times for the Young Male, Adolescent Male and Adult Male stimuli categories, as well as longer viewing times for the Adult Female slides, compared to the pedophilic child molesters. In addition, the AASI had the highest classification accuracy for the Pedophilic, Non-Antisocial molesters and the lowest classification accuracy for the Non-Pedophilic, Non-Antisocial child molesters. All molester groups, however, had problematic false positive and false negative rates. Admitting status was more related to pedophilic than antisocial status. The AASI was unable to accurately classify deniers, but demonstrated better discriminant validity for admitting molesters and partial deniers, who were classified with a similar degree of accuracy.
Supervision for convicted sex offenders.
Harlow, Michael C., Temporini, Humberto
Journal of the American Academy of Psychiatry and the Law, Vol 37(2), Jun, 2009. pp. 270-271.
Abstract:
The Abel Assessment for Sexual Interest (AASI-2), a screening tool for deviant sexual interests that measures visual reaction time, requires a test subject to view slides of clothed persons of varying ages and sexes, so that the person’s level of sexual attraction can be rated. In United States v. Stoterau, 524 F.3d 988 (9th Cir. 2008), Joseph Stoterau filed an appeal regarding the terms of supervised release ordered by the U.S. Central District Court of California. The court mandated that upon release from prison, Mr. Stoterau would be subject to Abel testing as a condition of his supervised release. In the case of United States v. Stoterau, the Ninth Circuit Court of Appeals clarified the scope of its previous ruling in United States v. Weber, 451 F.3d 552 (9th Cir. 2006). The Ninth Circuit Court of Appeals’ ruling that the AASI-2 does not significantly affect an individual’s interest in avoiding unwanted bodily intrusions and manipulations has an additional consequence: courts can mandate Abel testing in supervised release settings without having to provide a rationale.
The Abel Assessment for Sexual Interests – 2: A critical review.
Sachsenmaier, Susan J., Gress, Carmen L. Z.
Cognitive approaches to the assessment of sexual interest in sexual offenders. Thornton, David (Ed.); Laws, D. Richard (Ed.); pp. 31-57. Wiley-Blackwell, 2009. xiii, 236 pp.
Abstract:
(from the chapter) Limitations of the penile plethysmography (PPG) as an assessment technology have led to a search for a viable alternative. Subsequent chapters explore different alternatives. The best established of these alternatives—the amount of time that a subject views a possibly erotic stimulus—has been tested in various formats since 1942. This technique has been refined within the past 10 years and there are now two commercially available viewing time procedures. The Abel Assessment for sexual interest (AASI) was developed and it marketed by Abel Screening Inc. of Atlanta. This is a simple viewing time procedure which measures how long a subject looks at a stimulus. It is a commercial product exclusively marketed by Abel Screening who also controls administration procedures, scoring and data interpretation. The scoring algorithm is proprietary and has not been made available for independent empirical evaluation. This lack of peer review has raised concerns about the validity of the test. In Chapter 2, S. J. Sachsenmaier and C. L. Z. Gress review the evidence supporting use of this method, identify its limitations and propose circumstances when the method is appropriate for use and circumstances when it should not be employed.
Residential treatment for sexually abusive youth: An assessment of treatment outcomes.
Jones, Christopher D., et.al.
Research on Social Work Practice, Vol 20(2), Mar, 2010. pp. 172-182.
Abstract:
Objective: This research study assesses the effectiveness of participation in a multimodal/holistic residential treatment program on changing deviant sexual interests and functional impairment among sexually abusive youth. Method: A one-group pretest posttest design was utilized to examine pretest (intake) and posttest (discharge) scores for 58 youth between the ages of 9 and 18. Outcome measures included Child and Adolescent Functional Assessment Scale (CAFAS) and the Abel Assessment for Sexual Interest-Adolescent (AASI). Results: The results indicate significant improvement from pretest to posttest scores. Length of stay was not found to influence these impacts. Conclusions: The applications of these results to understanding the effectiveness of residential treatment for sexually abusive youth and the assessment of treatment outcomes for these youth are explored and discussed.
The Utility and Psychometric Properties of the Abel-Blasingame Assessment System for Individuals With Intellectual Disabilities
Blasingame, Gerry D., Abel, Gene G., Jordan, Alan, Wiegel, Markus
Journal of Mental Health Research in Intellectual Disabilities, Volume 4, 2011 – Issue 2
Abstract:
This article describes the development and utility of the Abel-Blasingame Assessment System for individuals with intellectual disabilities (ABID) for assessment of sexual interest and problematic sexual behaviors. The study examined the preliminary psychometric properties and evaluated the clinical utility of the ABID based on a sample of 495 male adults with intellectual disabilities and/or developmental delays. The study examined (a) length of assessment time; (b) the ability of test takers to distinguish between gender and between 4 age groups; (c) whether the ABID has internal consistency within the cognitive distortions, social desirability scale, and fantasy vignettes items; (d) the criterion validity of the ABID to detect sustained sexual interest in children; and (e) whether the use of the ABID questionnaire as a structured clinical interview increases awareness of information about an individual’s maladaptive behaviors important for treatment planning. The findings regarding these areas are discussed as well as the limitations of the tool in assessing individuals with intellectual disabilities.