A Pilot Study to Increase Chewing in Children With Feeding Disorders

Abstract

Children with feeding disorders often display chewing deficits. Unfortunately, there is a paucity of research examining procedures to increase or teach chewing to children with feeding disorders. The few studies on this topic have utilized multicomponent treatments typically involving a shaping procedure. In addition, to our knowledge, studies on chewing have not yet incorporated a product measure of chewing (whether the food is broken down enough to swallow after chewing), which we have termed mastication. In the current investigation, we evaluated relatively simple treatments to increase chewing with two children with a feeding disorder who were not chewing at clinically acceptable levels after treatment with nonremoval of the spoon. We also developed a product measure of chewing. In Study 1, we used a least-to-most prompting plus praise procedure to increase chews per bite in a typically developing child with a feeding disorder. We then used the results of Study 1 to refine treatment and develop our mastication measure for Study 2. In Study 2, we implemented a descriptive verbal prompt and praise procedure to increase chews per bite and percentage of mastication with one child with developmental delays and a feeding disorder.

Keywords

feeding disorder chewing prompting mastication

The chewing behavior of typically eating children emerges in a relatively predictable sequence. A child begins to chew at 6 months of age (Illingworth & Lister, 1964) and displays a loosely coordinated chewing pattern by 9 months of age (Stolovitz & Gisel, 1991). With experience, the efficiency of chewing improves over time in the absence of formalized intervention for most typically eating children. Parents provide the experience by introducing small amounts of soft or meltable table food and then by increasing the amount and difficulty of table food as they observe the child successfully manage the advanced textures. By 24 months of age, most children consume a diet that is largely composed of table food (Carruth, Ziegler, Gordon, & Hendricks, 2004) and display fully mature chewing skills by age 4 (Edwards & Martin, 2011; Schwartz, Niman, & Gisel, 1984).

Our clinical cobservation, by contrast, is that developmentally typical chewing patterns do not emerge in the same manner in children with severe feeding problems (Carruth et al., 2004; Carruth & Skinner, 2002). That is, they do not chew when presented with table food. Our patients display a wide variety of behaviors when presented with table food such as (a) expulsion of (spitting out) presented food, (b) pocketing the food (e.g., between the cheek and gum), (c) premature swallowing (i.e., swallowing the bite before it is masticated), (d) attempting to masticate food by pressing the bite to the roof of the mouth with the tongue, and (e) an immature munching pattern. It is not clear why chewing behavior does not emerge in the typical developmental sequence in children with feeding disorders, and an exploration of this issue is beyond the scope of this study.

One challenge to extending the literature on teaching chewing is that researchers have used a variety of definitions to define chewing behavior or have failed to provide an operational definition of chewing. For instance, Gisel (1994, 1996) and Gisel, Applegate-Ferrante, Benson, and Bosma (1995, 1996) measured vigor or duration of chewing; however, they did not provide an operational definition of chewing. Schwartz et al. (1984) and Schwaab, Niman, and Gisel (1986) defined a chewing cycle as an upward and downward movement of the chin. Chewing was not clearly defined in Butterfield and Parson (1973) and Sisson and Dixon (1986). Eckman, Williams, Riegel, and Paul (2008) defined chewing as an up and down movement of the jaw including contact of the upper and lower teeth at least 3 times within 5 s. Shore, LeBlanc, and Simmons (1999) defined chewing as a visible up and down motion of the jaw while food was visible in the mouth. The use of inconsistent or unclear operational definitions of chewing makes it difficult to compare the results of these studies.

Another limitation of the current chewing literature is that no studies on chewing have incorporated measures on mastication. Mastication is what we have defined as the product measure of chewing and provides an indication of the efficacy of the individual’s chewing behavior. That is, to consume high textured food safely (e.g., without aspirating), an individual must be able to not only chew the food but also chew it until it is sufficiently masticated to swallow safely.

Of the studies that examined chewing behavior, only a few focused on teaching chewing skills to children with feeding disorders. Butterfield and Parson (1973) used a treatment package to teach a child with Down syndrome to chew six different solid foods. The authors did not provide baseline data, but reported that the child did not chew table food. During treatment, the authors incorporated a modeling component that involved one caregiver biting a graham cracker to produce an audible “crunch” while the other caregiver praised the chew and provided a preferred food (cottage cheese). After the caregiver modeled chewing, the child was given a graham cracker and prompted to crunch (chew). The caregiver then provided enthusiastic praise and a spoonful of cottage cheese if the child chewed within 15 s of the verbal prompt and then this sequence was repeated. If the child did not chew after 15 s, the caregivers modeled the behavior again. This was repeated up to 5 times and if the child did not chew, the session was ended. The treatment package also included shaping. The authors instructed the caregiver to successively reinforce closer approximations of a chew until the child actually bit through the graham cracker. Cumulative number of chews increased from near 0 at the outset of treatment to almost 800 across approximately 40 days and chewing generalized to 5 new foods. Unfortunately, the treatment procedures were somewhat vague and the authors were not able to provide a demonstration of experimental control or determine which components of the complex treatment were responsible for the increase in chewing.

Eckman et al. (2008) used a combination of oral motor techniques along with shaping and fading to teach two children with a feeding disorder to chew. During baseline, the feeder instructed the child to take bites of dry, crisp foods (chewing sessions) or table-textured food (texture-fading sessions) and sessions lasted 10 min. During treatment, the feeder implemented nonremoval of the bite or cup and sessions were also 10 min (or nine bites for one participant). During chewing treatment sessions, the feeder placed a small amount of a crisp, dissolvable food onto the child’s molars and instructed the child to bite. The feeder provided praise and a preferred item for 10 s if the child bit through the food producing an audible sound. The feeder provided additional praise if the child met the definition of a chew (see above). The treatment package also included shaping and the feeder progressively increased the chew requirement. During texture-fading treatment sessions, the feeder presented a bite to the child and prompted the child to “take a bite.” When the child accepted the bite, the feeder delivered a verbal prompt to chew. The feeder also placed a small amount of yogurt or pudding in the corner of the child’s mouth and instructed the child to “lick the food.” Finally, a cup with 8 cc of a preferred liquid was given to the child to promote lip closure. The feeder provided praise and a preferred item for 10 s if the child chewed or approximated a chew, for tongue lateralization (if the child moved the tip of his or her tongue to the corner of the mouth), and after the child consumed the drink. During these sessions, the feeder faded the size (from a quarter or half spoon to a full spoon) and texture (ground to table food) of the bites using preset criteria. During baseline, chewing was zero for both children. During treatment, percentage of correct chewing increased and the feeder successfully advanced the texture to table food for both participants. Although the treatment package included components to address tongue lateralization and lip closure, data were not included on these variables. It was also unclear which component of the treatment was responsible for the increase in chewing and demonstration of experimental control would not be considered robust.

A few studies have examined procedures to encourage more appropriate chewing in individuals who already displayed some chewing skills (Shore et al., 1999; Sisson & Dixon, 1986). For example, Shore et al. (1999) increased chews per bite using prompting, shaping, and reinforcement in one child diagnosed with severe developmental delays and an esophageal stricture who displayed a history of rapid eating that resulted in food being caught in his esophagus. During the final treatment phase, the feeder placed a plate of food in front of the child and delivered verbal cues to take bites every 30 s. The feeder provided corrective feedback and blocked the child’s hand if he attempted to take bites too soon and corrective feedback for taking bites considered too large. Finally, the feeder provided social praise and a juice if the child chewed a specified number of times before swallowing. The chew requirement was progressively increased by two based on the mean number of chews from the two prior meals. During treatment, number of chews per bite increased from 5 to near 25; however, experimental control was not demonstrated for the chewing component of treatment.

Many of the aforementioned studies used multicomponent treatments to increase chewing and also gradually shaped the number of required chews. We wondered whether a relatively simple treatment (least-to-most prompting plus praise or descriptive prompting and praise procedure) that did not involve a shaping component would be effective for increasing chews per bite in two children with a feeding disorder. Therefore, we tested this treatment with the first child in Study 1. We used her data to refine treatment and develop a measure of mastication, which we used in the treatment of the second patient in Study 2.

General Method

Participants and Setting

Mia was a typically developing 4-year-old female whose medical history included failure to thrive, reflux, and vomiting. Mia primarily consumed Carnation Instant Breakfast (CIB) and pureed and wet ground foods (pureed texture with small chunks). Mac was a 14-year-old male whose medical history included developmental delays, prematurity, bronchopulmonary dysplasia, tracheostomy, failure to thrive, reflux, fundoplication, and gastrostomy-tube dependence. Mac received 80% of his nutritional needs via oral consumption of CIB, and he consumed small amounts of solid foods, which mostly consisted of a pureed texture.

Both participants had a previous history of food refusal that we successfully treated using nonremoval of the spoon prior to the outset of this study. The goal of the current treatment was to increase the texture of solid food. For both participants, we observed minimal chewing when we advanced the texture from pureed or wet ground to table food. That is, Mia often mashed table food using her tongue, and Mac frequently failed to chew food to mastication during baseline observations. A physician cleared both participants as safe oral feeders. Per parental report, neither participant choked while attempting to consume table foods at home. In addition, choking did not occur during our treatment analyses for either participant. We conducted weekly 1-hr appointments in a 4 m × 4 m outpatient room equipped with one-way observation and sound. Session materials included feeding utensils (e.g., bowl, spoon), a booster seat (Mia), table and chairs, a scale, a timer, and laptop computers.

Data Collection and Interobserver Agreement

We defined a chew as each time the child’s teeth and/or jaw completed one up-and-down motion with the teeth parted at least 1.3 cm while food was visible in the mouth (however, if food was visible on the center of the tongue, we did not score this as a chew), independent of all prompting in baseline for Mia. Observers used the same definition to score chewing following the verbal prompt in baseline for Mac and treatment for both participants. Observers recorded the occurrence of chews using laptop computers and calculated chews per bite by dividing the number of chews by the number of bites that entered the child’s mouth. For Mac, we defined mastication as food with pieces no larger than 0.2 cm × 0.2 cm in a liquid medium after chewing. Observers recorded mastication once per bite and calculated a percentage after dividing the number of bites masticated by the number of mastication checks (mastication could not be scored when Mac swallowed before showing the feeder the bite, which rarely occurred). We defined a pack as any food, rice size or larger, that remained in the child’s mouth 30 s after the bite entered the child’s mouth (baseline for both participants and treatment for Mac) or 30 s following mastication of the bite for Mia during treatment.

Two individuals assessed interobserver agreement during 27% and 23% of sessions for Mia and Mac, respectively. Observers were individuals with bachelor’s, master’s, or PhD degrees in psychology, behavior analysis, or a related field. Data collectors were all trained to criterion (agreement of 80% or higher for three consecutive sessions) on the operational definitions using didactic instruction, rehearsal, and feedback. We calculated interobserver agreement by breaking the session into successive 10-s bins. We considered an agreement when both observers scored at least one response in an interval or if both observers scored no responses in the interval. We then summed occurrence and nonoccurrence agreements, divided by the sum of occurrence and nonoccurrence agreements and disagreements, and converted this ratio to a percentage. Mean interobserver agreement was 94% (range = 60%-100%) and 81% (range = 50%-100%) for chews for Mia and Mac, respectively. Mean interobserver agreement was 99% (range = 92%-100%) and 98% (range = 92%-100%) for packs for Mia and Mac, respectively. For Mac, mean interobserver agreement was 94% (range = 82%-100%) for mastication.

Experimental Design

We used a concurrent multiple baseline design across foods to demonstrate experimental control. We used visual inspection procedures to determine when to implement treatment and whether treatments were effective to increase chews per bite and percentage of mastication (Mac only).

Procedure

General Procedure for Studies 1 and 2

Prior to the first session of an appointment, the feeder explained the contingencies for acceptance, chewing, and mouth clean (converse of pack) and packing only when further intervention was necessary to decrease packing for Mia. The feeder did not state again unless the procedures changed during the appointment. Sessions consisted of five bite presentations. The feeder presented one 0.6 cm × 0.6 cm piece of food on a spoon in an empty bowl every 30 to 45 s with the verbal prompt “Take a bite.” Although the goal was for the child to chew each bite, the pieces were small enough for the child to swallow without choking so that the chew training did not pose any risk to the child (i.e., the child would not aspirate if he or she swallowed the bite without chewing). The feeder provided praise (e.g., “Good job taking your bite”) if the child self-fed the bite within 5 s of presentation. If the child did not self-feed the bite within 5 s, the feeder used nonremoval of the spoon (Hoch, Babbitt, Coe, Krell, & Hackbert, 1994) in which she held the spoon at the child’s lips until the child opened his or her mouth such that the feeder could deposit the bite into the child’s mouth. The feeder provided no differential consequences for inappropriate behavior. To check for mouth clean or pack, the feeder prompted the child to “Show me.” If the child did not open his or her mouth, the feeder placed the spoon to the lips and physically guided the mouth open. If the child had no food rice size or larger in his or her mouth, the feeder provided praise (e.g., “Good job swallowing your bite”). If the child had food the size of a grain of rice or larger, collectively, in his or her mouth at the check, the feeder prompted the child to “Swallow your bite.” Neither participant engaged in expulsion throughout the analysis due to their long histories with nonremoval of the spoon and re-presentation.

Study 1 (Mia)

Procedure

General

A trained therapist served as the feeder. The feeder used the general procedure described above with the following additions. During each session, the feeder presented one food, canned green beans, carrots, peaches, potatoes, or apricots; club crackers; frozen fish sticks prepared in microwave; or Tyson grilled chicken on a small maroon© spoon. If Mia initiated conversation during the session, the feeder conversed with her. The feeder presented the next bite after the mouth clean check independent of whether Mia had swallowed. A speech therapist approved this procedure because Mia did not typically hold more than the equivalent of two bites in her mouth at one time. If Mia was packing after the feeder presented the fifth bite, the feeder checked every 30 s and prompted Mia to “Swallow your bite,” until no food rice size or larger was visible in her mouth or 10 min elapsed from the start of the session. If food was in Mia’s mouth at the 10-min mark, the feeder removed the food from her mouth with the spoon.

Baseline

The feeder did not instruct Mia to chew and did not provide praise for chewing. The feeder conducted the check for mouth clean 30 s after the bite entered her mouth.

Treatment

Once the bite entered Mia’s mouth, the feeder prompted her to “chew eight times.” The chew requirement we selected for treatment was based on Schwartz et al. (1984). These authors concluded that 4- and 5-year-old typical children chewed raisins or graham crackers an average of 15.5 times, which was also consistent with chewing performance of older children and adults. We reduced the chew requirement because the foods were softer than a raisin or graham cracker. The feeder used a least-to-most prompting procedure (verbal, gestural, physical) to prompt Mia to chew. If she did not chew within 5 s of the verbal prompt (chew 8 times) or stopped chewing for 5 s before completing eight chews, the feeder modeled chewing and prompted her, “Chew like this.” After the model prompt, if Mia did not chew within 5 s or stopped chewing for 5 s before completing eight chews, the feeder physically guided eight chews or the remaining chews. For example, if Mia chewed 5 times but then stopped chewing after the feeder delivered the model prompt, the feeder physically guided Mia to chew 3 more times. Physical guidance consisted of the feeder placing one hand on top of Mia’s head just above her forehead and the four fingers of the other hand under Mia’s chin with the thumb of the same hand horizontally on her chin while gently providing upward and downward pressure to move her jaw. The feeder counted each chew aloud. The total number of chews was always eight, independent of what level of prompting the feeder used. The feeder provided verbal praise (“good job chewing”) when Mia completed eight chews without physical guidance.

During baseline, we observed that Mia may have been swallowing some of her bites whole. Thus, during treatment, the feeder conducted an additional mouth check after Mia completed eight chews to determine whether Mia had masticated the food. The feeder provided no differential consequence for mastication. If the food was not masticated, the feeder instructed Mia to chew 4 more times using least-to-most prompting followed by a mouth check. The feeder repeated the four-chew prompting and mouth check until Mia had masticated the food. Once Mia had masticated the food, the feeder conducted a mouth check 30 s later and then presented the next bite. That is, Mia had an additional 30 s to swallow after she had masticated the bite. The feeder continued to provide praise for mouth clean and chews completed without physical guidance.

Results and Discussion

Figures 1 and 2 show chews per bite for Mia. For green beans, chews per bite were low during baseline (M = 1.6, range = 1-2.2) and increased during treatment (M = 8.3, range = 7.8-10). For apricots, chews per bite were low during baseline (M = 1.3, range = 1-1.6) and increased to a high level during treatment (M = 7.4, range = 6.4-8). For peaches, chews per bite were low and variable during baseline (M = 1.2, range = 0-3.4) and increased during treatment (M = 7.4, range = 5-8). For carrots, chews per bite were variable during baseline (M = 3.5, range = 1.6-5.4) and increased to a high, stable level during treatment (M = 8). For potatoes, chews per bite were moderate to low during baseline (M = 3.2, range = 2.6-3.8) and increased during treatment (M = 8.2, range = 7-10). For fish sticks, chews per bite were variable during baseline (M = 2.3, range = 0.2-4.4) and increased to a high level during treatment (M = 8.7, range = 7.2-11.2). For chicken, mean chews per bite were highly variable during baseline and decreased prior to treatment (M = 4.1, range = 0.4-9.6). During treatment, chews per bite increased to a more stable level (M = 8, range = 6.4-10.4). During baseline for crackers, chews per bite were variable (M = 4.9, range = 0.6-13.6). We did not implement the chewing intervention with crackers due to time constraints. Although mastication was not a dependent variable, percentage of mastication was high during treatment for all foods.

Figure 1.

Chews per bite for green beans, apricots, peaches, and carrots.

Figure 2.

Chews per bite for potatoes, crackers, fish sticks, and chicken.

Mia engaged in near-zero levels of packing across baseline and treatment for apricots and peaches and during baseline for crackers. For green beans, packing was 100% during baseline and decreased to low levels during treatment (M = 17%, range = 0%-60%). For carrots, packing was variable during baseline (M = 34%, range = 0%-80%) and decreased to 0% during treatment. For potatoes, packing was 60% during baseline and although variable, decreased during treatment (M = 30%, range = 0%-100%). For fish sticks, packing was 100% during baseline and did not decrease with the least-to-most prompting plus praise treatment (M = 90%, range = 80%-100%). For chicken, packing was high during baseline (M = 83%, range = 60%-100%) and also did not decrease during the least-to-most prompting plus praise treatment (M = 87%, range = 60%-100%). For fish sticks and chicken, we implemented a flipped spoon procedure as described in Volkert, Vaz, Piazza, Frese, and Barnett (2011) to decrease packing to a mean of 8% (range = 0%-40%) and 10% (range = 0%-20%), respectively (data available on request).

A limitation of Study 1 is that the feeder delivered the verbal prompt immediately after the bite entered Mia’s mouth during treatment but not during baseline; thus, we could not measure independent chewing in treatment. It is possible that the verbal prompt to chew alone would have increased chewing. We provided the model prompt during a total of 10 sessions and we only used physical guidance during the second treatment session with peaches. In addition, it was not entirely clear whether the prompting sequence, counting Mia’s chews aloud, or praise increased Mia’s chewing. Due to the immediate increase in chews per bite and the fact that we reviewed the rules prior to the session, it is also possible that Mia engaged in rule-governed behavior. Thus, it is unclear which component of treatment was responsible for the increase in chewing.

Another limitation of Study 1 is that Mia had 30 s to chew and swallow her bite during baseline but a potentially longer period of time during treatment due to the extra time to swallow the bite following mastication. As a result, it is possible that the increase in chewing (and decrease in packing for green beans, carrots, and potatoes) during treatment may have been the result of Mia having additional time to chew (or swallow the bite). However, within-session analysis of the treatment data indicate that this was not the case because Mia engaged in all chews per bite in a mean of 6.4 s (range = 3-34.8 s) following the bite entering her mouth for all foods and chewing occurred after 30 s for only one bite across all treatment sessions (data available upon request).

Study 2 (Mac)

In Study 2, we attempted to address some of the limitations of Study 1. That is, we provided a verbal prompt and praise for chewing across baseline and treatment, and we evaluated fewer treatment components (e.g., discontinued least-to-most prompting, counting chews aloud). To further prevent the possibility of choking, we no longer presented new bites if Mac was packing. In addition, we measured mastication across baseline and treatment.

Procedure

General

Mac’s mother served as the feeder. The feeder used the general procedure described above with the following additions. During each session, the feeder used a metal teaspoon to present one food, canned green beans or peaches; frozen french fries prepared in microwave; or hotdog. The feeder checked for a mouth clean 30 s after the bite entered his mouth. If Mac was packing the bite, the feeder prompted him to “swallow your bite” and continued to check his mouth every 30 s until no food, rice size or larger, was visible in his mouth before presenting the next bite or ending the session if he packed the fifth bite.

Baseline

The feeder prompted Mac to “chew and swallow” when the bite entered his mouth. The feeder instructed Mac (prior to the session) to show his mouth before he swallowed to determine whether the food was masticated if this occurred before the 30-s check. Otherwise, the feeder checked for and the data collector scored mastication during the mouth clean check. The feeder did not provide additional prompts to chew during the check or differential consequences for mastication. The feeder provided general praise (good job chewing) for chewing the appropriate number of times (10 or 15).

Treatment

Once the bite entered his mouth, the feeder provided a descriptive verbal prompt to chew (i.e., “Chew 10 times” for green beans, peaches, or french fries and “Chew 15 times” for hotdog). At the mouth clean check or if Mac showed his mouth before swallowing, the feeder provided descriptive verbal praise (i.e., “Good job chewing 10 [15] times”) if he chewed the required number. If Mac did not chew the required number, the feeder instructed him to “chew your bite 10 (15) times next time.” The feeder continued to provide praise for mouth clean regardless of whether he chewed the required number of times. To begin to advance the bolus to a more age typical size, we probed an increased bite size of 1.3 cm × 1.3 cm × 0.6 cm.

Results and Discussion

Figure 3 shows chews per bite for Mac. For green beans, chews per bite were variable during baseline (M = 5.7, range = 1.4-13.4) and increased during treatment (M = 12.9, range = 5.2-21.2). For hotdog, chews per bite were variable and on a decreasing trend during baseline (M = 6.1, range = 1.2-11.2) and increased during treatment (M = 15.5, range = 8.4-27.6). For peaches, chews per bite were variable during baseline (M = 4, range = 0.4-10.6) and increased to more stable levels during treatment (M = 11.2, range = 9.2-14). The treatment was not implemented with french fries due to time constraints and the fact that chews per bite were on an increasing trend (M = 7.7, range = 3.4-17.6). Chews per bite remained high for all foods during the probes with increased bite size.

Figure 3.

Chews per bite for green beans, hotdog, peaches, and french fries.

Figure 4 shows percentage of mastication for Mac. For green beans, percentage of mastication was variable but at low to moderate levels overall during baseline (M = 33.3%, range = 0%-33.3%). Although the percentage of mastication remained variable, mastication increased to higher levels during treatment (M = 75.6%, range = 25%-100%). For hotdog, percentage of mastication was variable during baseline (M = 31.7%, range = 0%-80%) and increased to high levels during treatment (M = 61.6%, range = 20%-100%). For peaches, percentage of mastication was variable but low overall (M = 36.8%, range = 0%-100%) and increased to more stable and high levels during treatment (M = 83.3%, range = 50%-100%). Percentage of mastication remained low and variable with french fries with no intervention in place (M = 32.8%, range = 0%-100%). Percentage of mastication remained high during the probes with a larger bite size with all foods.

Figure 4.

Percentage of mastication for green beans, hotdog, peaches, and french fries.

For green beans and peaches, packing was low overall across baseline (M = 23%, range = 0%-80%; M = 2%, range = 0%-20%, respectively) and treatment (M = 11%, range = 0%-40%; M = 12%, range = 0%-40%, respectively). For hotdog, packing was high during baseline (M = 84%, range = 40%-100%) and, although variable, decreased during treatment (M = 43%, range = 0%-100%). Packing was variable but moderately, low with french fries independent of intervention (M = 37%, range = 0%-100%).

With Mac, we provided a verbal prompt and praise for chewing across baseline and treatment. Thus, it appeared that the more descriptive verbal prompt and praise were responsible for the increases in chewing and mastication. During the session that we increased the bite size for french fries, chews per bite and mastication increased to higher levels. Thus, it is possible that simply increasing the bite size alone would have increased chewing and mastication in the absence of treatment.

General Discussion

We successfully increased chews per bite in two children diagnosed with a feeding disorder using fairly simple treatment procedures. We also developed and evaluated a procedure to measure and increase mastication, which had not been done to our knowledge prior to the current investigation.

A limitation of the study is that we defined chewing as an up and down motion of the jaw as previous researchers (e.g., Eckman et al., 2008; Shore et al., 1999). We did not include tongue lateralization and rotary jaw movement or the collection of the masticated food on the middle of the tongue in the definition of chewing. These behaviors are more difficult to observe unless the child chews with an open mouth, which is an atypical eating behavior. Future research is needed to evaluate treatments to measure and increase more complex chewing behavior. Our measure of interobserver agreement for chewing could also be considered limited because an interval was scored as an agreement as long as each observer scored at least one chew. Another concern is that a high chews per bite were not always associated with a high level of mastication for Mac. Thus, future research should develop a method to measure force of chewing. Another limitation of our study is that we used a relatively small bite size. Because these children displayed some chewing during baseline, it is possible that chewing may have increased if we had simply increased the bite size.

We provided praise for mouth clean across phases regardless of whether the bite was masticated; thus, we may have actually reinforced early swallowing. The check for mastication should be conducted sooner (e.g., 10 to 15 s following the bite entering the child’s mouth) in future research to have a better chance of observing whether the child masticated the bite before swallowing. For Mac, we used an instruction to show the feeder his mouth before he swallowed. Although Mac still sometimes swallowed before the mouth check, we were able to score mastication most of the time (i.e., on four of the five bites on average across baseline and treatment).

Despite these limitations, this study is important clinically because it is the first to demonstrate the effectiveness of prompting procedures and praise in the absence of shaping or fading as treatment for chewing. In addition, it is also the first study to evaluate whether increases in observable chewing resulted in masticated food.

Although these procedures were effective in this study, they may not be appropriate for children who have no underlying chewing skills and very poor oral motor skills. Both Mia and Mac appeared to engage in some chewing; thus, we may have only increased compliance with chewing a greater number of times rather than have taught the skill of chewing. Regardless, noncompliance with chewing is problematic, and we were able to increase chews per bite. Future studies should evaluate the relative effectiveness of the various procedures with children who have differing underlying chewing and oral motor skills.

Footnotes

Acknowledgements

Thanks to Lara Barnett and Erin Feind for their assistance with this study.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Author Biographies

Dr. Volkert is an Associate Professor at the University of Nebraska Medical Center. She received a Bachelor’s of Science from the University of Florida, and she received her Ph.D. in School Psychology from Louisiana State University in 2007. Dr. Volkert completed her post-doctoral fellowship at the Munroe-Meyer Institute with Dr. Cathleen Piazza as her mentor.

Dr. Piazza received her doctorate from Tulane University in New Orleans, LA. Dr. Piazza was a faculty member at JHUSM and KKI where she was the Chief Psychologist of the Neurobehavioral Unit, the director of Training, and the director of the Pediatric Feeding Disorders Program. In 1999, she became director of the Pediatric Feeding Disorders Program and the Training Program at the Marcus Institute in Atlanta and she is currently a Professor in Pediatrics at University of Nebraska Medical Center (UNMC) and the director of the Pediatric Feeding Disorders Program at the Munroe-Meyer Institute.

Dr. Vaz received her Ph.D. from Ohio University and her major was dysphasia. She is a certified speech-language pathologist.

Jana Frese worked as a behavior analyst specialist for five years in the Pediatric Feeding Disorders Outpatient Program at the Munroe-Meyer Institute. She was a master clinician with a specialty in chewing.

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