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Temple Grandin Hug Machine: How did Weighted Blanket Research Begin?

Temple Grandin is one of the pioneers associated with deep pressure therapy with the Temple Grandin hug machine. Here we read about how it's paved the way for..

The Temple Grandin Hug Machine marked the beginning of all things deep pressure stimulation which in turn –later– initiated the weighted blanket research trend.

We have articles written to deconstruct deep pressure stimulation, as well as some studies that utilize alternative methods of deep pressure stimulation other than weighted blankets. Today’s post will steer away from the norm in the sense that it will encompass various articles and dive into an alternative deep pressure stimulation application — the Temple Grandin hug machine. Her device has been referred to as Temple Grandin’s squeeze machine and calming device hug box, but these are all terms that refer to the same device.

This post will discuss some of the histories behind deep pressure stimulation, inform how the hug box was invented, and notate a couple of results from people who used deep pressure stimulation in the different forms. My previous posts have touched on the effects of deep pressure stimulation through various means such as weighted blankets, weighted vests, and partnered applied pressure, but have you ever stopped to wonder how and when pressure application as a form of therapy was developed?

History of Deep Pressure Stimulation: How the Temple Grandin Hug Machine Started it All

Deep pressure stimulation use goes all the way back to the middle ages. In mental institutions, chains for restraint were replaced with straight jackets when clinicians caught on to the change in behavior as a result of the pressure from the straight jackets. The use of straight jackets was discontinued due to the belief that using them was unethical, and instead, solitary confinement was introduced and implemented as a distress reduction tactic (Hunter & Macalpine, 1963). They basically replaced something helpful, with something very unhelpful. 

Anecdotal evidence of the benefits associated with deep pressure stimulation before it was labeled and studied came from Takagi and Kobayasi (1955) and Harlow and Zimmerman (1959). Takagi and Kobayasi (1955) found that when deep pressure was applied to the body, the body relaxed as evidenced by a decrease in heart rate, metabolic rate, and muscle tone. Those of you who are psych majors will recall that Harlow and Zimmerman (1959) tested baby monkey’s preference of mother, where they chose a soft cloth model of a mother over a wire model.

Though the anecdotal evidence stems from the 1950s, Temple Grandin was one of the people who later initiated the surge of deep pressure stimulation research. Grandin had symptoms of autism which were apparent at the age of two, however at the time those who were diagnosed typically stayed in an inpatient psychiatric hospital. She was not officially diagnosed until she was in her 40s.

Temple Grandin (1992), an animal scientist, came across the idea of a hug machine while on a relative’s farm. As she was observing cattle squeeze through chutes (basically a cow hug machine). She noticed they came out of the chutes noticeably calmer. The chute provided deep pressure stimulation against most of the animal’s body.

Grandin experimented with several designs and eventually perfected her protocol; she named it the Temple Grandin Hug Machine.

Temple Grandin Hug Machine

The hug machine provided users control, where they could choose how much pressure they received, and leave at any point in time. She reported that by using the device frequently, she was able to withstand touches from other people and the anxiety symptoms she once felt, were now subsided (Grandin, 1992).

She originally constructed the hug machine to alleviate her own symptoms of autism, but upon finding great success, she expanded her search to determine if it would help others.

The Temple Grandin Hug Machine on Other Populations

Average Adults and the Hug Machine

Grandin (1992) recruited college students between the ages of 18-25 who were recruited to test the hug machine for 5-10 minutes, and then give feedback. This was a qualitative study, meaning the students were interviewed by researchers afterward where researchers compiled answers and searched for themes.

Interview Answer Compilation

temple grandin hug machine opinions from a sample size.

Researchers asked 25 of the students: What would you use this machine for if you were to buy it within a store?

  • 17 students noted they would use the machine for a relaxing tool or tension reliever.
  • One of the students who did not have a relaxing sensation following the use of the hug machine reported that he would use it as an isometric exerciser.

Another Variation Of The Experiment

Eighteen students used the squeeze machine in one of the randomly selected ways:

  • Sustained Stationary Pressure Applied
  • Fast Rhythmic Pulsation (50 squeezes per minute).
  • Slow Rhythmic Pulsation (15 squeezes per minute).
weighted blankets help with anxiety
(Grandin, 1992)

Shifting Weight On Your Own

Although weighted blankets do not provide pulsating weights as the hug machine does, you can adapt. You can double-up the blanket to increase pressure and then gradually reduce the amount of weight against your skin or vice versa if you would like to increase your weight gradually. To get a pulsating action, you will need a partner, but this can also be achieved using a weighted blanket.

Squeeze machines can be purchased, but for a pretty penny. For $2000 you may buy a squeeze machine form Therafin Corporation. Although, you may find cheaper (and less space-consuming) remedies elsewhere such as weighted blankets, weighted vests, or gym mats (and a partner).

Children who have autism and the squeeze machine

Edelson, Goldberg, Edelson, & Grandin (1998)  studied the previous literature on DPS (including some of the articles we have addressed in previous posts and in this one) and were still skeptical on the value of DPS, so they examined the literature that was available and addressed the flaws from each study. Their goals were:

  • To determine whether deep pressure stimulation has any effect on anxiety
  • To determine if there were any physiological changes in anxiety with deep pressure stimulation
  • To determine if there were any side effects associated with deep pressure stimulation

The participants included 12 children (9 males, 3 females) who had been diagnosed with autism by their primary care provider; Their ages ranged from 4 to 13 years. The symptoms they experienced varied with some children who were nonverbal and others with the ability to hold a conversation. Unlike other studies that used a sample size with a similar severity in symptoms, this study sought to include a wide variety of impairments to test the effects amongst a more variable population.

The children were split into two groups where one received the experimental treatment (the hug machine), and the other received the control. The researchers attempted to match a control participant to an experimental participant in terms of symptom severity, age, and gender so that results could be more comparable.

Three measurements were used in this study:

  • Galvanic skin response (or as we have referred to it before electrodermal activity). We have touched on this measurement before, but as a recap, this was used to measure sweat secretions. The more sweat = more anxiety. Skin conductance was measured before and right after the child utilized the hug machine.
  • Conner’s Parent Rating Scale. This assessment contains 93 items related to various symptoms, not all of which the researchers were interested in, so they customized the scale to include only those questions related to anxiety both emotionally and physically. Parents rate their child from 1 – 4, where 1 = the child does not seem impacted to 4 – the child is impacted very much. It goes without saying that the larger the score on this assessment, the more anxiety is observed. Parents were asked to fill out this survey before the first session, and after the sixth and twelfth session. The parents did not know which group their child was assigned to and thus were blinded.
  • A side effects questionnaire was developed to determine if there were any side effects as a result of the treatment (hug machine or control). There were two open-ended questions that the parents were asked to complete at the start of each week.

All of the children were introduced to the hug machine so that they could gain comfort with it. After a couple of introductory sessions, the procedure began. The children utilized the hug machine twice a week for six weeks in 20-minute increments. Both children were in the hug machine, but the control group’s lever was disengaged, thus preventing them from experiencing DPS.

The sample size used means that this study cannot be generalized and is merely a pilot study (or initial study). However, the results showed that DPS did have an impact on anxiety and children experienced no side effects. Both parent report surveys and electrodermal activity showed a decrease in anxiety levels when the hug machine was used compared to those that were in the control group.

anxiety decreases with deep pressure stimulation
Restlessness Scores Based on Conner’s Scale (Edelson, Goldberg, Edelson, & Grandin, 1998).
restlessness with weighted blanket
Anxiety Scores Based On Conner’s Scale (Edelson, Goldberg, Edelson, & Grandin, 1998).
anxiety scores with weighted blanket
Tension Scores Based On Conner’s Scale (Edelson, Goldberg, Edelson, & Grandin, 1998).

Other Versions of Deep Pressure Stimulation: Case Studies with Children

Case studies are different in the sense that they look at individuals or groups in depth. The case studies described below tracked the journey of two participants and how deep pressure stimulation shifted their symptoms.

A 13-year old male who was diagnosed with autism presented to an inpatient psychiatric hospital for “pinching, biting, and rubbing of his head, neck, trunk, and upper and lower extremities” (McClure & Holtz-Yotz, 1991). The treatment team developed arm splints that constricted the chid’s movement and prevented him from picking at the skin behind his neck.

The treatment team noticed that as time went on, the client’s picking subsided, so they were able to remove the splint. After the splint was removed, the client sought out other sources to simulate the sensation in which the splint provided. The treatment team concluded that along with providing a restriction for symptom engagement, the splint also acted as a deep pressure stimulation tool and benefited the client in that way (McClure & Holtz – Yotz, 1991).

Zisserman (1992) followed an eight-year-old female who held the diagnoses of “severe developmental delay, possibly seizures, and autism,” struggled with apparent distress during occupational therapy and school. The child sought out self-stimulating behaviors that were similar to deep pressure stimulation, so the therapist constructed wraps from panty-hoes to provide pressure to the child’s arms. The therapist then studied the behavior differences and took note of the number of times the child would engage in self-stimulating behaviors (such as banging her hands against the table) with and without the wraps on her arms.

arm wrap helps with anxiety
(Zisserman, 1992)

Considerations for those who want to use Deep Pressure Stimulation

  • There are multiple mechanisms available to deliver deep pressure stimulation, some allow an individual to deliver deep pressure stimulation to themselves, while others require a partner.
  • Duration of deep pressure stimulation required, depends on the individual. Some may find that they achieve benefits in as little as five minutes, whereas others may need longer durations.
  • Some people may approach deep pressure stimulation with acceptance and be willing to deliver the sensation to themselves, whereas others may approach the phenomena with more hesitancy. Grandin reports that through her observations, she finds people with ADHD are more likely to be receptive to deep pressure stimulation, whereas those with autism may need more information and encouragement before attempting deep pressure stimulation.
  • Some people may need varying pressures, they may wish to start with lower pressure and gradually increase, or they may need quick pulses or slow pulses.

Moral Of The Story

Experiment! Find out what feels right for you and what will meet your needs. No two people are alike, and although research is needed to determine what works for the masses, that doesn’t always mean the results will apply to you.

I’d love to hear how you guys use your weighted blankets that go against the norm!


Edelson, S., Goldberg, M., Edelson, D., & Grandin, T. (1999). Behavioral and physiological effects of deep pressure on children with autism: A pilot study evaluating the efficacy of Grandin’s hug machine. American Journal of Occupational Therapy, 53(2), 145-152. doi:10.5014/ajot.53.2.145

Grandin, T. (1992). Calming effects of deep touch pressure in patients with autistic disorder, college students, and animals. Journal of Child and Adolescent Psychopharmacology, 2(1), 63-71. doi: 10.1089/cap.1992.2.63

Harlow, H., & Zimmerman, R. (1959). Affectional responses in infant monkey. Science, 130, 421-432.

Hunter, H., & Macalpine, I. (1963). Three hundred years of psychiatry, 1535 – 1860. London: Oxford University Press.

McClure, M., & Holtz-Yotz, M. (1991). The effects of sensory stimulatory treatment on an autistic child. American Journal of Occupational Therapy, 45(12), 1138-1142. doi:10.5014/ajot.45.12.1138

Takagi, K., & Kobayasi, S. (1955). Skin pressure vegetative reflex. Acta Medical et Biologica, 4, 31-37.

Zissermann, L. (1992). The effects of deep pressure on self-stimulating behaviors in a child with autism and other disabilities. American Journal of Occupational Therapy, 46(6), 547-551. doi: 10.5014/ajot.46.6.54

Veronica THWB

Veronica is a mental health professional who is pursuing a doctorate in Clinical Psychology. She has earned her master’s degree in Clinical Mental Health Counseling and now provides therapy to children and youth in the community agency setting. She has been a part of several studies withiфn the field of psychology, including cognitive psychology, sports psychology, and health psychology. Her current research interests revolve around utilizing mindfulness meditation techniques and how they can impact the health of individuals in various socio-economic settings. She also has research interests revolving around developing and implementing interventions to aid in recovery from substance abuse within the primary care setting.

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