The Effect of Verbalization on the Face Perception of Children with Autism Spectrum

Disorder

Thesis

Presented in Partial Fulfillment of the Requirements for the Degree Master of Arts in the

Graduate School of The Ohio State University

Minje Kim

Graduate Program in Psychology

The Ohio State University

2019

Thesis Committee

Marc J. Tassé, Ph.D., Advisor

Luc Lecavalier, Ph.D.

Susan Havercamp, Ph.D.

Copyrighted by

Minje Kim

2019

Abstract

The purpose of this study was to examine whether giving verbal description of the face can enhance the face recognition ability of individuals with Autism Spectrum Disorder (ASD).

Participants in the current study were 18 individuals with ASD and 18 typically developing individuals (TD) with their full-scale IQ and age matched. The computerized experiment, which consisted of three experimental conditions, was conducted. Participants were exposed to three experimental conditions for a minute in a counterbalance order: 1) verbalization: giving verbal descriptions of the target faces 2) Navon: reporting global letters of the Navon stimuli 3) control: watching the video clip of a man riding a snowboard.

The results showed a significant interaction effect between groups and conditions. Further analysis revealed that individuals with ASD reported higher accuracy in discriminating targets in the verbalization and Navon conditions than in the control condition. This result suggests that the face recognition ability of the individuals with ASD can be enhanced via verbal description of the face. Clinical implication and limitation of the study are further discussed.

Vita

2014 …………………………… B.A. Psychology, B.A. Business Administration, Korea University 2016 …………………………… M.A. Clinical Psychology, Yonsei University 2017 to Present ……………… Doctoral Program in Intellectual and Developmental Disability, The Ohio State University

Publications

Chung, K. M., Kim, M., Koo, Y. Y., Ko, C. K., Kim, D. H., & Kim, S. J. (2016) Effects of Intensive and House Tutoring on Math Grade of College Students. Journal of Research in Curriculum & Instruction, 20(6), 459-469.

Kim, M., & Chung, K. M. (2016). A Review of Behavior Interventions for Joint Attention in Children with Autism Spectrum Disorder. Korean Journal of Clinical Psychology, 35(2), 557-583.

Fields of Study

Major Field: Psychology

iii

Acknowledgements

This thesis was completed as the graduation requirement of graduate program in psychology in Yonsei University, South Korea, with the advisor, Kyong-mee, Chung, Ph.D.

Table of Contents

Abstract ...... ii Vita ...... iii Acknowledgements ...... iv Table of Contents ...... v List of Tables ...... vii List of Figures ...... viii Chapter 1. Introduction ...... 1 Social cognition ...... 1 Face perception ...... 2 Weak central coherence model ...... 3 Strategies for enhancing face recognition: Navon letters ...... 4 Strategies for enhancing face recognition: Verbalization ...... 4 Research Questions ...... 5 Chapter 2. Method ...... 6 2.1 Participants ...... 6 2.2 Measurements ...... 7 2.2.1 Autism Diagnostic Observation Schedule-2; ADOS-2...... 7 2.2.2 Autism Diagnostic Interview-Revised; ADI-R ...... 7 2.2.3 Korean-Wechsler Intelligence Scale – IV...... 8 2.2.4 General Health Questionnaire ...... 8 2.3 Materials and Apparatus ...... 8 2.3.1 Apparatus ...... 8 2.3.2 Stimuli ...... 9 2.4 Design and Procedure ...... 10 2.4.1. Experimental Design ...... 10

2.4.2. Experimental Procedure ...... 10 2.5. Data Analysis ...... 12 Chapter 3. Results ...... 13 3.1. Analysis of Mean Accuracy ...... 13 3.2. Analysis of Mean Reaction Time ...... 13 Chapter 4. Discussion ...... 14 Bibliography ...... 28

List of Tables

Table 1. Demographic Characteristics of Participants ...... 20 Table 2. Comparison of Demographic Characteristics ...... 20 Table 3. Interaction Effect and Post-hoc Analysis on Mean Accuracy of the Face Recognition Task ...... 21 Table 4. Repeated measures ANOVA on Mean Accuracy of Face Recognition Task. .... 21 Table 5. Interaction Effect and Post-hoc Analysis Mean Reaction Time on the Face Recognition Task ...... 22 Table 6. Repeated measures ANOVA on Mean Reaction Time of Face Recognition Task ...... 22

vii

List of Figures

Figure 1. Recruiting Procedure ...... 23 Figure 2. Example of Face Stimuli ...... 24 Figure 3. Example of Navon Stimuli ...... 24 Figure 4. Example of Control Stimuli...... 24 Figure 5. Experimental Procedure ...... 25 Figure 6. Repeated measures ANOVA on Mean Accuracy of the Face Recognition Task ...... 26 Figure 7. Repeated measures ANOVA for Mean Reaction Time of the Face Recognition Task ...... 27

viii

Chapter 1. Introduction

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social interaction and communication, along with the presence of restricted and repetitive behaviors and limited interests (DSM-5; American Psychiatric Association,

2013). Deficits in social interaction and communication include trouble with understanding and communicating appropriately in a variety of social contexts (Landry & Loveland,

1989), difficulties in communicating via conventional nonverbal cues (Mundy, Sigman,

Ungerer, & Sherman, 1986), and lack of social-emotional reciprocity (McIntosh,

Reichmann-Decker, Winkielman, & Wilbarger, 2006) (DSM-5; American Psychiatric

Association, 2013).

Social cognition

Social cognition, defined as a mental process involving perceiving, remembering, and understanding people in a social context (Brothers, 1990; Moskowitz, 2005), has gained attention from researchers as a main mechanism for deficits in social interaction and communication in the ASD group (Adolphs, Sears, & Piven, 2001; Pelphrey, Adolphs,

& Morris, 2004; Tager-Flusberg, 1999). Studies in social cognition have shown that, compared to typically developing (TD) individuals, individuals with ASD have difficulties in attributing other’s mental state (Theory of Mind, ToM) (Baron-Cohen, Leslie, & Frith,

1985; Ozonoff & Miller, 1995), and in interpreting others’ emotion (Face Emotion

Recognition, FER) (Bal et al., 2010). Additional evidences from recent studies using brain- imaging techniques showed reduced activity in brain regions responsible for social cognition such as the superior temporal sulcus and the amygdala in the ASD group compared to the TD group (Sugranyes, Kyriakopoulos, Corrigall, Taylor, & Frangou, 2011).

Face perception

On the other hand, another line of research has investigated perceptional process of faces in relation to social deficits based on the fact that face has substantial information required in social interactions, such as gender, identity, and emotion (Haxby,

Hoffman, & Gobbini, 2002, Schultz, 2005). These studies found that individuals with

ASD exhibited difficulties in voluntarily directing attention to a person’s face

(Swettenham et al., 1998), as well as face recognition (Williams, Goldstein, & Minshew,

2005). In addition, researchers found that individuals with ASD experience perceptual difference from TD individuals when processing a face. The face inversion effect, which is a phenomenon that individuals show poorer performance on identification of inverted faces than upright face, is a representative example (Freire, Lee, & Symons, 2000; Joseph

& Tanaka, 2003). Individuals with ASD does not show inferior performance in recognizing an inverted face compared to an upright face. Another example of perceptual difference is the face composite effect, which is described as a difficulty in identifying the top half of a familiar face when it has been aligned with the bottom half of a different face (Mondloch, Pathman, Maurer, Le Grand, & de Schonen, 2007; Rossion, 2013;

Young, Hellawell, & Hay, 1987). Studies found that individuals with ASD did not

2 experience difficulties in identifying the composited face (Gauthier, Klaiman, & Schultz,

2009; Teunisse & de Gelder, 2003).

Weak central coherence model

One explanation for this characteristic impairment in face perception in people with ASD is the weak central coherence model (WCC; Frith, 1989; Happé, 2005). This model is based on the finding that individuals with ASD process information with a locally biased processing strategy (Happé & Frith, 2006), while the TD individuals globally process incoming information (Happé & Frith, 2006; Joseph & Tanaka, 2003;

Mondloch, Pathman, Maurer, Grand, & Schonen, 2007). Therefore, the distorted configuration would lead to a disturbed holistic processing and a poorer performance on a face identification task of TD individuals. On the contrary, the individuals with ASD did not show decreased performance in identifying the inverted face or composited face, because they do not utilize holistic processing like TD individuals (Lahaie et al., 2006;

Langdell, 1978).

The WCC is also supported by another line of research; individuals with ASD showed superior performance over TD individuals on the Block Design Task (Shah & Frith,

1993), which requires analytical thinking about the segmented features. In addition, they exhibited superior performance on the Embedded Figures Task (Shah & Frith, 1983) compared to TD individuals, where they had to find hidden shapes in drawings as quickly as possible. Also, inferior performance of individuals with ASD than TD individuals in the

Sentence Completion Task, which requires information processing on a global level, supports the WCC as well (Happé, 1997).

Strategies for enhancing face recognition: Navon letters

Little efforts have been made to identify an effective method of enhancing face recognition in ASD. Few possible strategies have been suggested from the literatures in TD adults, which showed that face recognition could be improved through enhancing global processing (Behrmann et al., 2006; López, Donnelly, Hadwin, & Leekam, 2004). For example, experimental procedures of repetitively identifying global letters of the Navon letter, a large alphabetic letter composed of smaller letters (Navon, 1977), could facilitate participants to focus on the global configuration and engage in holistic processing.

Likewise, identifying the local letters of the Navon letters could facilitate participants to engage in local processing (Lewis, Mills, Hills, & Weston, 2009; Weston, Perfect, Schooler,

& Dennis, 2008). The studies utilizing Navon letters consistently reported that the individuals who identified global letters outperformed the individuals who identified local letters in the following face recognition task (Hills & Lewis, 2007; Lewis et al., 2009;

Macrae & Lewis, 2002; Weston et al., 2008).

Strategies for enhancing face recognition: Verbalization

Additionally, it has been reported that verbalization, a process of verbally describing a face, can enhance face identification (Brown, Gehrke, & Lloyd-Jones, 2010;

Brown & Lloyd-Jones, 2006; Jung & Chong, 2012; Weston & Perfect, Schooler, & Dennis,

2008) through facilitating participants to carefully attend to the configuration of a face

(Nakabayashi et al., 2012). Few studies found that participants who verbally described the face performed better in the face recognition task compared to participants who did not verbally describe the face (Brown, Gehrke, & Lloyd-Jones, 2010; Brown & Lloyd-Jones,

2006). In addition, the results revealed that verbalization about the face, as short as 15 seconds, was associated with group differences.

Research Questions

The purpose of the current study is to examine 1) the difference in face recognition ability between the ASD group and TD group, and 2) to investigate the effectiveness of enhancing global processing with verbalization and the Navon task on the face recognition ability by comparing the performance of face recognition task between experimental conditions.

Chapter 2. Method

2.1 Participants

Individuals with ASD of aged between 8 and 25 years were recruited through online advertisements, local clinics and hospitals. Among 33 participants with ASD who were recruited, 18 individuals met the following inclusion criteria for this study: 1) individuals who scored above the diagnostic cutoff for autism in both the Autism

Diagnostic Observation Schedule -2 (ADOS-2) (Lord et al., 2002) and Autism Diagnostic

Interview-Revised (ADI-R) (Lord et al., 1994), 2) whose full-scale IQ was above 70, and

3) who reported no history of mental or physical illness other than ASD on the General

Health Questionnaire (Kim, Chung, Rhee, Ryu, Won, & Shin, 2011), and 4) whose performance in the face recognition task is above the chance rate (50% or more) in at least one of three conditions.

Age and gender-matched typically developing youth were recruited through online community for parents with school aged children as a control group. The inclusion criteria for the TD group involved: 1) who reported no history of mental or physical illness on the

General Health Questionnaire (Kim et al., 2011), and 2) full-scale IQ above 70, and 3) performance in the face recognition task above the chance rate (50% or more) in at least one of three conditions were included in the experiment (Figure 1). The demographic characteristics of the participants are shown in Table 1. This study was approved by the

Institutional Review Board of Yonsei University (201311-SB-157-01) and all participants were recruited after receiving the approval.

2.2 Measurements

2.2.1 Autism Diagnostic Observation Schedule-2; ADOS-2

The ADOS-2 is a semi-structured assessment tool for screening autism spectrum disorder (Lord et al., 2002) and was standardized in Korea by Yoo and Kwak (2007).

Module 2, 3, and 4 are conducted according to the participants’ developmental stage. The

ADOS-2 was conducted by trained research assistants under the supervision of the second author who obtained the research reliability for ADOS-2 administration. Participants who met the cut-off score for autism diagnostic criteria of ADOS-2 and ADI-R were included in the ASD group.

2.2.2 Autism Diagnostic Interview-Revised; ADI-R

The ADI-R is the structured interview for screening autism spectrum disorder

(Lord, Rutter, & Le Couteur, 1994), standardized in Korea (Yoo, 2010). The interview consists of 93 items and was conducted via interview with the primary caregivers. The interview covered the children’s early development, acquisition and loss of language and other skills, social development and play, and repetitive, limited interests and behaviors.

The ADI-R was administered along with the ADOS-2 by trained interviewers under the supervision of the second author who obtained research reliability for ADI-R administration. Participants who scored higher than the cut-off score for autism diagnosis of ADI-R and ADOS-2 were included in this study.

2.2.3 Korean-Wechsler Intelligence Scale – IV

The Korean-Wechsler Intelligence Scale for Children-Fourth Edition (K-WISC-

IV) (Kwak, Oh, & Kim, 2011) and Korean-Wechsler Adult Intelligence Scale-Fourth

Edition (K-WAIS-IV) (Hwang, Kim, Park, Chey, & Hong, 2012) were administered to evaluate the participant’s intellectual ability. This test consists of four subscales: Verbal

Comprehension Index, Perceptual Reasoning Index, Working Memory Index, and

Processing Speed Index, and the results obtained also yield a full-scale IQ (FSIQ). Trained examiners under the supervision of certified clinical psychologists administered the

Korean-Wechsler Intelligent Scale. Participants whose FSIQ is was above 70 were included in the study.

2.2.4 General Health Questionnaire

The General Health Questionnaire (Kim et al., 2011), was used to acquire information about the demographic characteristics and health status of participants. This questionnaire was used to screen 1) ASD participants for mental or physical illness other than ASD and 2) TD participants for chronic disease and medication use other than health supplements. Parents evaluated participants’ general health status, medical history and current medication using the 7-point Likert scale, with 1 being very poor and 7 being very healthy.

2.3 Materials and Apparatus

2.3.1 Apparatus

Participants were individually taken into a room in the university isolated from outside noise and natural light and were left alone with an experimenter. They were seated

8 facing a computer 50 centimeters away with an experimenter located to the right of the participants. The experimental procedure was controlled with the Microsoft computer, which had an operating system of Windows XP. All the stimuli were presented on a white background in the center of a 15-inch CRT monitor. The entire experiment was programmed using PsychoPy 2.0 (Peirce, 2007).

2.3.2 Stimuli

Face Stimuli. Randomly selected neutral faces of 15 males and 15 females from the Korea University Facial Expression Collection (KUFEC) (Lee, Lee, Lee, Choi, &

Kim, 2006) were used. All the face stimuli were presented from a frontal view with a neutral facial expression. In order to prevent participants from recognizing target faces by distinctive features such as hair, or moles, all faces were edited to fit into a circle that was

1.54 cm wide and 2.01 cm high and colors were adjusted into grayscale via Adobe

PhotoShop CS6 in order to mask their distinctiveness (see Figure 2 for a sample).

Navon Stimuli. The Navon letters were obtained from the first author of Lee and his colleagues’ article (2012) via e-mail upon request. Twelve combinations of 'A', 'E',

'H', and 'S' were used for the Navon condition (e.g. large ‘H’ consists of small ‘A’s)

(Figure 3). Navon letters used in the current study were presented in Arial font. Each local letter was of size 1.3 x 1.3°, and each global letter was of size 10 x 15°.

Control Stimuli. A visual scanning task using a video clip was selected as a control task, since it does neither require excessive cognitive resources nor produce distraction (Nakabayashi, Burton, Brandimonte, & Lloyd-Jones, 2012). The criteria for selecting a video clip were as follows; 1) the background should remain fairly constant

9 throughout the clip, and should not be distracting, 2) there should only be one main character whose face is not shown throughout the clip (the main character should only be recognized by his or her silhouette), and 3) the main character should have a consistent pattern of movement. A video of a man riding a snowboard was selected as the control task with e-mail permission from the producer (Retrieved 16 August 2014, from http://www.youtube.com/watch?v=EFyZ58FmKCw)1. For the experiment, the video was edited into five consecutive clips that were one-minute-long each (Figure 4).

2.4 Design and Procedure

2.4.1. Experimental Design

The experiment had a 2 x 3 design with the two groups of participants (ASD and

TD) as between-subject variables, and three conditions (verbal, Navon, and control) as within-subject variables. Accuracy rate and response time were collected as dependent variables.

2.4.2. Experimental Procedure

All participants completed three experimental conditions (verbal, Navon, and control), and the sequence of the conditions was counterbalanced across participants

(Figure 5). Each condition consisted of 2 phases: a study and a recognition phase. In the study phase, the participants were shown a target stimulus for 3500ms. Then, they were instructed to perform the assigned task for each condition for one minute, which was repeated five times using five target faces. A recognition phase was followed, in which participants were asked to respond whether a presented face was previously seen or not. A

1 The video was removed from the site in 2015, hence inaccessible at this point. 10 total of ten faces was presented individually, including five target faces. Participants were instructed to respond by pushing an appropriate keyboard (‘Z’ = target face, ‘M’ = new face).

Verbal Condition. In the verbalization condition, participants were asked to verbally describe a presented face for a minute. Considering the limited verbal ability of the ASD group, a checklist with descriptions of a face was utilized. The checklist consisted of 21 descriptions of faces including eyes, eyebrows, nose, and mouth. Under each feature heading was a set of 5 point bipolar scales with adjective descriptors reflecting various characteristic of a feature (i.e., had small eyes vs. had big eyes). The participants were asked to complete the checklist and to verbalize an adjective descriptor to the experimenter during the one-minute segment (i.e., a participant who checked a box closer to the description ‘had small eyes’ would say ‘he had relatively small eyes’).

Navon Condition. In the Navon condition, participants were asked to report the global letters of a series of Navon letters. Each letter was presented randomly for 2500ms.

In each trial, a total of 12 Navon letters was presented twice for one minute. For each incorrect response, corrective feedback was provided instantly, and participants’ responses were recorded.

Control Condition. In the control condition, participants were asked to watch a one-minute video clip of a man riding a snowboard for a minute. If a participant looked away from the screen, a verbal prompt was given to look at the video clip. No responses were given to any attempt to communicate with an experimenter during this condition.

2.5. Data Analysis

The IBM SPSS (Statistical Package Social Science) statistics 21.0 was used for all data analyses. The dependent variables were mean accuracy and reaction time in the face recognition task. A repeated measure ANOVA was conducted to examine the interaction effect of groups by conditions, and main effect of the group and the condition. In addition, a post-hoc test using Bonferroni was carried out to examine whether there was a significant difference between conditions within each group.

Chapter 3. Results

3.1. Analysis of Mean Accuracy

The repeated measure ANOVA was conducted to analyze the mean accuracy data

(Figure 6). The results showed a significant interaction between conditions and groups (F(2,

34) = 3.954, p < .05). The post-hoc test, using Bonferroni correction method, showed that

ASD group performed significantly better in the verbalization and Navon conditions compared to the control condition (p < .05). However, no significant difference was found between the verbalization and Navon conditions (p > .05). Also, the TD group did not show any significant differences across conditions (p > .05) (Table 3).

In addition, a significant main effect for group was found. The TD group performed significantly better compared to the ASD group (F(1, 34) = 8.188, p < .01).

Significant main effect of the conditions was also found (F(2, 34) = 8.290, p < .01).

Regardless of the group, participants showed higher accuracy on the face recognition task in the verbal and the Navon condition than the control condition (p < .05). Again, no difference between the verbal and the Navon condition (p > .05) (Table 4) was found.

3.2. Analysis of Mean Reaction Time

The results of the repeated measures ANOVA on the mean reaction time data showed no interaction effect between groups and the conditions (F(2, 34) = 1.261, p > .05)

(Table 4 and Figure 6). No main effects for conditions and groups were found (p > .05).

Chapter 4. Discussion

The current study was conducted to find whether there are differences in performance on a face recognition task between 18 individuals with ASD and 18 typically developing individuals. In addition, the current study investigated whether enhancing global processing strategy with Navon and the verbalization condition can improve the face recognition ability of the ASD group. Participants were exposed to all three experimental conditions each for one minute in a counterbalanced order: 1) verbalization: giving verbal descriptions of the target faces; 2) Navon: reporting global letters of the Navon stimuli; and

3) control: watching the video clip of a man riding a snowboard. Mean accuracy and reaction time in the face recognition task were measured. For mean accuracy, the results showed a significant interaction effect between the groups and conditions. The post-hoc analysis showed that individuals with ASD performed significantly better in the verbal and the Navon conditions over the control condition. No difference was found in mean accuracy between the verbal and the Navon conditions in ASD group. There was no significant difference in accuracy across conditions within TD group. Lastly, the TD group showed superior performance over the ASD group and participants of both groups showed better performance in the verbal and the Navon condition than the control condition. On the other hand, no significant difference was found in the analysis of mean reaction time. The implications and discussions of the results are as following.

The statistically significant group differences found in the face recognition task are consistent with results from the previously published studies that showed deficit in face recognition for people with ASD (Arkush, Smith‐Collins, Fiorentini, & Skuse, 2013;

Boucher & Lewis, 1992; Klin et al., 1999; Williams, Goldstein, & Minshew, 2005). These results indicate that the ASD group might have perceptual differences compared to TD individuals. However, the face recognition tasks used in previous studies utilized multiple distractors and quarter view stimuli, making the tasks more challenging. The current study, on the other hand, utilized the old-new decision task, and presented the same set of stimuli with full-frontal views both in study and recognition phases, making it a comparably simpler task. As a result, the accuracy rate of the TD group in the current study was as high as 75%, yet, the ASD group showed about 50% level of accuracy across the conditions, which is nearly a chance rate. Considering the level of difficulty of the face recognition task, the results of the current study indicate perceptual difference as a possible mechanism of the impaired face recognition ability of the ASD group.

In a review of published behavioral studies (Weigelt, Koldewyn, & Kanwisher,

2012) suggested that perceptual differences such as atypical eye contact of the ASD group may be relevant to the impaired recognition performance of face identity. In addition, a series of studies on norm-based coding model, which explains how people use their internal norms to process the face, found that the ASD group was less capable of updating face norms, compared to the TD group (Ewing, Leach, Pellicano, Jeffery, & Rhodes, 2013;

Pellicano, Jeffery, Burr, & Rhodes, 2007). These results support the possible relationship between perceptual differences and the face recognition ability of the ASD group.

Additional studies are needed to investigate how these perceptual differences of the ASD group may have an effect on the face recognition ability. For example, atypical eye contact may be associated with insufficient information of the eye region to update the face norm, leading to the impaired performance in the face recognition task (Fiorentini, Gray, Rhodes,

Jeffery, & Pellicano, 2012).

The positive results shown in the verbal and Navon conditions may be related to enhanced global processing. For example, Nakabayashi and her colleagues (2012) revealed that verbalization could modulate the learning procedure of the face. Specifically, the eye- movement of the participants showed a greater distribution among the features of the face when they were asked to verbalize about the face. These results indicate that the verbalization of a face can help participants allocate their attention to specific regions of the face, and facilitate global processing. In addition, researchers who utilized the Navon task often suggested that identifying global letters could facilitate global processing while identifying local letters could enhance local processing (Kimchi, 1992). It was reported that participants showed better performance during the face recognition task when identifying global letters of the Navon stimuli (Macrae & Lewis, 2002; Weston et al., 2008).

Considering how global processing can facilitate the performance in a face recognition task, the enhanced performance of the ASD group in the verbalization and Navon conditions could be attributed to an increase in global processing. This result also supports the WCC model, which explains locally biased processing of individuals with ASD. It is possible that the effect of WCC was compensated with the enhanced global processing due to the verbalization and Navon conditions.

The current study showed that a simple and short experimental manipulation is sufficient to enhance face recognition ability among individuals with ASD, suggesting the possibility of using both verbalization and the Navon task as elements of an intervention to improve social skills in this population. The result is very encouraging considering that the most common treatment for improving social skills often involves direct training from clinicians (White, Keonig, & Scahill, 2007), which is expensive, time-consuming, and requires trained professionals (Ramdoss et al., 2011; Ramdoss et al., 2012). Since face recognition ability is considered to be a key skill in the development of social competence

(Dawson, Webb, & McPartland, 2005), computerized programs utilizing verbalization and the Navon task might be effective strategies to improve the face recognition ability and social skills of people with ASD.

The current study has a number of limitations within which these findings must be interpreted. First, our sample size was slightly smaller than the recommended to yield adequate statistical power. A priori power analysis suggested that minimum number of 44 participants would be needed to yield medium effect size (f = 0.25) in repeated-measures

ANOVA. However, the current study was able to recruit only 36 participants. Therefore, the results of the study should be interpreted with caution. Second, the current study recruited a wide range of participants whose chronological ages were between 8 and 25 years. Further research should examine whether the verbalization has a differential effect in accordance to participants’ age. Third, the current research revealed that the verbalization and the Navon task can improve face perception ability of ASD group.

Further studies should investigate the mechanism behind such improvement. In order to

17 explain this mechanism, additional experimental manipulation is needed. For example, the condition of identifying local letters of Navon stimuli could be included to explain more about the Navon condition. Finally, the current research measured the cognitive ability of participants with ASD and recruited participants whose FSIQ was higher than 70; however, this is certainly not the complete picture of the ASD population. Recent report from Center for Disease Control and Prevention (CDC) indicated that 30% of people with ASD has

FSIQ below 70 (Baio et al., 2018). Therefore, this requirement may possibly limit the generalization of the study results. As a result, in order to develop an intervention program that can be implemented to the general ASD population, further study should consider including participants with various levels of cognitive ability.

Both the verbalization and Navon conditions have useful clinical implications for intervention. Therefore, each condition can be administered according to individual characteristics. For example, for individuals with ASD whose language is severely impaired (Guerts & Embrechts, 2008), the Navon task, rather than the verbalization procedure, might be recommended. The Navon task can also present a practical advantage for children with ASD who have superior visual information processing over verbal information. On the other hand, for the subgroup of individuals with ASD, whose language ability is intact, the verbalization condition might be a practical treatment option. In addition, practicing verbalization is a relatively convenient procedure to utilize at home since it does not require additional materials. Moreover, the language-based program can provide a chance to practice language skills, which is considered as a pivotal skill to various social interaction skills (Lewis, Boucher, Lupton, & Watson, 2000). These are important

18 implications for intervention with potential benefits for people with ASD, and warrant for future researches to test their effectiveness in clinical settings.

The current research, however, could not find any evidence to support the effects of verbalization in the TD group. Effects of verbalization among TD individuals are controversial. A meta-analysis study by Meissner & Brigham (2001) found an interfering effect associated with verbalization, which they called as verbal overshadowing effect

(VOE). The VOE, a phenomenon in which giving a verbal description of a face is associated with the decreased performance of a face identification task (Schooler &

Engstler-Schooler, 1990), suggesting the possibility that verbalization has an interfering effect. However, the current study showed no change in performance after verbalization, supporting neither the facilitating nor interfering effect of verbalization. The most plausible reason for the inconsistency of results may be due to the difference in experimental procedures. For example, the current study differed from the previous research in terms of task materials (i.e., video clip, photo, real-person), and task-type (Meissner & Brigham,

2001). Also, a ceiling effect might also explain the difference in results since the average accuracy performance of the TD group in this study was over 75%. In addition, as noted in the limitation, a small number of participants might be the source of insignificant results.

A larger number of participants might yield a different result.

Table 1. Demographic Characteristics of Participants

Elementary Middle High Adult Total School School School 18 ASD M 10 4 2 2 (50%) (n=18) F 0 0 0 0 0 (0%) 14 TD M 7 5 1 1 (39%) (n=18) F 2 1 1 0 4 (11%) Total(%) 19 10 4 3 36 (n=36; %) (53%) (28%) (11%) (8%) (100%)

Note: Elementary School = age 7-12; Middle School = age 13-15; High School = 16-18; Adults = age 18-25.

Table 2. Comparison of Demographic Characteristics

Group ASD TD t df p n 18(M=18) 18(M=14) Mean Age (SD) 158.94(42.70) 161.06(29.89) -.172 34 .865 Mean FSIQ (SD) 95.17(17.16) 103.44(13.20) -1.622 34 .114 Note: The mean age of participants was calculated in month. M = male

Table 3. Interaction Effect and Post-hoc Analysis on Mean Accuracy of the Face Recognition Task

Condition Group

ASD TD

F significance M(SD) M(SD) Condition x Group

Verbal .76(.15) .78(.14)

Navon .70(.16) .80(.11) 3.954 .024*

Control .57(.14) .75(.14)

Note. *p< .05

Table 4. Repeated measures ANOVA on Mean Accuracy of Face Recognition Task.

Effect F significance

Main Effect

Group 8.188 .007**

Condition 8.290 .001**

Interaction Effect

Group x Condition 3.954 .024*

Note. *p< .05, **p< .01

Table 5. Interaction Effect and Post-hoc Analysis Mean Reaction Time on the Face Recognition Task

Condition Group

ASD TD

F Significance M(SD) M(SD) Condition x Group

Verbal 2.09(1.23) 1.69(0.42)

Navon 1.69(0.47) 1.70(0.55) 1.261 .290

Control 1.62(0.54) 1.53(0.39)

Note: The mean reaction time of face recognition task was calculated in seconds.

Table 6. Repeated measures ANOVA on Mean Reaction Time of Face Recognition Task

Effect F significance

Main Effect

Group 1.022 .391

Condition 2.607 .081

Interaction Effect

Group x Condition 1.261 .290

Figure 1. Recruiting Procedure

Figure 2. Example of Face Stimuli

Figure 3. Example of Navon Stimuli

Figure 4. Example of Control Stimuli

Figure 5. Experimental Procedure

1 0.9 0.8 0.7

0.6 ASD 0.5 TD 0.4

0.3 Mean Accuracy Mean 0.2 0.1 0 Verbal Navon Control

Figure 6. Repeated measures ANOVA on Mean Accuracy of the Face Recognition Task

2.5

ASD 1.5 TD

1 (in seconds)(in

Mean Reaction Time Reaction Mean 0.5

0 Verbal Navon Control

Figure 7. Repeated measures ANOVA for Mean Reaction Time of the Face Recognition Task

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