The Science Behind Our Mobile Tasks

What if cognitive testing took place early and often? What if people could be empowered to change their behavior? What if cognitive research could deliver personalized, simple, and actionable recommendations to improve health? Consider the impact of detecting risk factors and digital biomarkers to improve patient outcomes. This is the value of Savonix. We leverage our powerful database of cognitive, lifestyle, and other health data to assess and monitor your brain health over time.

Our clinically validated, neurocognitive test provides real-time results for: instant and delayed verbal memory, impulse control, attention, focus, emotion identification, information processing speed, flexible thinking, working memory, executive function, visual learning, and spatial memory.

The Role of Memory in Dementia

Memory impairment is not always the first symptom of dementia disorders. Studies show that up to 20 percent of people who later develop dementia show no signs of memory impairment in the early stages and that impairments in one domain alone are often benign.1 In contrast, studies have also shown that multidomain assessment can pick up a range of cognitive problems at an early stage and up to 60 percent of people who later develop dementia present with multidomain impairments at the mild cognitive impairment (MCI) stage.2

20% of people who later develop dementia show no signs of memory impairment in the early stages.

60% of people who later develop dementia present with multidomain impairments in the early stages.


Verbal Memory Recognition Task

This task includes immediate and delayed verbal memory recognition. In 1916, Édouard Claparède published the Test de mémoire des mots (Test of Memory for Words), a list of 15 words accompanied by a set of instructions for using the list as a measure of cognitive function (Boake, 2000). This test would become the basis for André Rey’s Auditory Verbal Learning Test (AVLT; Rey, 1964), and subsequent tests of verbal learning, including the Savonix Verbal Learning Task. Though Claparède’s test has been modified from its original form, it has been in near continuous use for the past 100 years, and similar tests are considered a “gold standard” in the field of cognitive assessment for verbal memory. The Rey AVLT (1964; Schmidt, 1996) is the basis for the Savonix Verbal Learning Task. Like many modern tests of verbal learning, it presents patients with a list of words, which are to be committed to memory. Patients are tested on their ability to remember the words immediately after the original list is removed, and then again after at least a 15-minute delay. The recognition trial of the AVLT, the most similar condition to the Savonix task, has been demonstrated to have high test-retest reliability (r= 0.72; Delaney, et al., 1992), and the AVLT as a whole compares favorably to other tests in terms of its ability to discriminate between patients and controls (Powell, Cripe, & Dodrill, 1991). The academic journal search tool Google Scholar lists 19,900 articles that reference the Auditory Verbal Learning Test.

Go/No-Go

The Go/No-Go task has been widely used in research and clinical practice to measure response inhibition and impulse control. In Alexander Luria’s highly influential, Higher Cortical Functions in Man (2012; originally published in 1962), Luria describes a method for presenting subjects with varying auditory stimuli, some requiring a response and some requiring no response. In this task, the subject is presented with two stimuli and must respond to one while not responding to others. Another method used by Luria, in the Savonix version, a green circle is presented frequently (Go) and a red square infrequently (No-Go) on the screen. The subject is required to inhibit the screen tap responses on the square and tap quickly on the circle when presented. Versions with visual stimuli have been widely used for the past 60 years. Neuroimaging studies have found that frontal lobe functions underlie performance on the Go/No-Go task. In the Savonix version of this traditional method, our mobile task measures response accuracy, response time, and errors of commission and omission. This data is used to assess the capacity for suppressing automatic responses.

Verbal Interference

Savonix’s Verbal Interference Test is based on the Stroop effect (Dodrill, 1978). The Stroop effect has been widely used in clinical and research settings for the past 50 years as an accurate measure of cognitive control and processing speed. John Ridley Stroop first published research on this in English in 1935 (Stroop, 1935), though it had been previously discovered. Stroop described an experiment where participants were presented with color words such as red, yellow, green, or blue, which were printed in a different color of ink (e.g., red printed in blue ink). Participants were able to easily read the words but found it more difficult to name the color of the ink. Stroop observed that the learned response of reading the words “interfered” with the unfamiliar task of naming the ink color. Naming the ink color requires inhibiting the well- practiced, interfering tendency to read words. This ability to inhibit a practiced response is similar to situations individuals are faced with in their day-to-day lives. The Savonix Verbal Interference task measures focus by assessing the subject’s ability to inhibit automatic and irrelevant responses. Additionally, people with dyslexia experience more interference when reading the colors of words than those without dyslexia. Scientists had originally hypothesized that people with dyslexia would experience less interference because reading is more challenging, and therefore they would be able to bypass reading in favor of reporting color. However, the larger degree of interference suggests that reading is such an automatic process and difficult to suppress whether or not reading comes easily (Everatt, 1997). The Stroop test is often used to gauge the severity of ADHD (Mishra 2016). The academic journal search tool Google Scholar lists 102,000 articles that reference the Stroop test.

N-Back

Savonix’s N-back task is based on a procedure described by Muriel D. Lezak in her book, Neuropsychological Assessment (2004). This task has been widely used in research settings for the past 20 years. The first example of N-back was in Psychology of Aging by Dobbs and Rule (1989). In the Savonix task, users are presented with a sequence of stimuli on the screen and asked to indicate when the current stimulus matches the one from ‘n’ steps earlier in the sequence. The load factor ‘n’ can be adjusted to make the task more or less difficult. 1-N means that you have to remember the position of the item, ONE turn back. 2-N means that you have to remember the position of the item TWO turns back, and so on. A 1-back is used in the child’s version of the assessment, and a 2-back is used in the adult version. The outcome variables include response times and number correct and incorrect. This is a measure of sustained attention in a continuous performance task. N-back also tests working memory, that is, how well a subject can temporarily hold information and then replace it with new information as needed. N-back is commonly used to assess patients with disorders that are associated with poor working memory, such as schizophrenia and multiple sclerosis (Sweet 2011). Additionally, this task caught media attention in the 2000s as a way to improve fluid intelligence. This idea was based on a study by Jaeggi et al. (2008) that linked working memory training through the N-back task with better performance on reasoning and problem-solving tasks. The academic journal search tool Google Scholar lists 11,700 articles that reference the N-back test.

Emotion Identification

The Savonix Emotion Identification task was developed based on protocols used in research studies (e.g., Hornak, Rolls, & Wade, 1996). Ekman and Friesen’s (1975) pioneering work on facial expressions forms the basis of this work and has been used in research settings for decades. The Savonix version of this task uses facial images with different facial expressions (surprise, fear, disgust, happy, sad, neutral). Recognition of facial emotions is a complex process that has profound implications for rehabilitation of patients with brain damage who exhibit socially inappropriate behavior. Hornak and colleagues (1996) found that patients with frontal lobe damage who exhibited inappropriate behavior also showed impairments in recognition of facial expression of emotions, indicating that these areas are implicated in this task.

Trail Making Task

The Trail Making task is based on the classic test developed by Reitan (1958), used frequently since its development. Part A of this task is a measure of visual scanning and information processing speed. The user is presented with a pattern of 13 numbers (1-13) on the screen and is required to touch numbers in ascending sequence (i.e., 1, 2, 3...). As each number is touched in correct order, a line is drawn automatically to connect it to the preceding number or letter in the sequence. This allows the user to visualize the path touched.

The outcome variable is time to completion as well as number of correct responses versus incorrect responses. Part B of this task is a measure of cognitive flexibility and attention switching. The user is presented with a pattern of 13 numbers (1-13) and 12 letters (A-L) on the screen and is required to touch numbers and letters alternatively in ascending sequence (i.e. 1, A, 2, B, 3, C...). As each number or letter is touched in correct order, a line is drawn automatically to connect it to the preceding number or letter in the sequence. This allows the user to visualize the path touched. The outcome variable is time to completion as well as number of correct responses versus incorrect responses in comparison with results from Trail Making Part A. Level of education and age are the two factors that affect scores the most. More education correlates with better scores. While accuracy remains relatively constant over age, older subjects tend to take longer to complete the trail and thus have a lower score (Meyers 2011). Snyder performed a meta-analysis of studies describing neuropsychological measures of executive function in patients with major depressive disorder (MDD) in 2013. The meta-analysis found that patients with MDD performed worse on both Trail Making Part A and B. The manual for administering the Trail Making test has been cited over 1,300 times in scholarly works (Reitan 1986). Overall, the academic search tool Google Scholar notes 48,100 articles that refer to the Trail Making test.

Maze Task

Maze learning is a classic experimental condition used in both humans and animals to investigate specific learning and memory functions. Many maze tasks exist and have a rich history in neuropsychological testing, the Porteus Maze (Porteus, 1965) and NAB Maze (Stern and White, 2003) as examples. The Savonix Maze task is similar to the procedure reported by Milner (1965). The Milner Maze is sometimes referred to as the Austin Maze. In Milner’s task, bolts were attached to a wooden board. No markings were on the board; subjects were required to discover the path of the “maze” through trial and error. When subjects touched the bolts with a metal-tipped stylus, a sound would alert the subject if they were on the right path. The Savonix test is similar in principle to the Milner Maze, but the maze is displayed on a device screen and feedback is provided visually rather than auditorily. Milner’s (1965) study examined the sensitivity of his maze task to hippocampal, frontal lobe, and cerebellar lesions.

Complex Figure Copy Task

Savonix’s Complex Figure task is based on the figure test first developed by Rey (1964) and standardized by Osterrieth (1944). The Rey-Osterrieth Complex Figure Test (ROCF) is a measure of visual spatial memory, and has been used clinically to evaluate attention, planning, and executive function. The ROCF or similar tests have been used for the past 50 years, and have high reliability and internal consistency (Berry, 1991). The Savonix Complex Figure task adapts the method developed by Rey and Osterrieth for a touchscreen device. Similar to the ROCF, the outcome variable of the Savonix Complex Figure is accuracy of the reproduced figure against the original figure, as measured by errors versus correct features. Consistent with the ROCF, following at least a 15-minute delay period, a free recall is administered in which subjects attempt to redraw the original design from memory. Both delayed cued and free recall memory paradigms have been identified as being important measures used in evaluating Alzheimer’s disease (e.g. Papp et al., 2015). Older individuals tend to require more time to complete the complex figure task compared to younger people. It is commonly used to assess dementia (Bigler, 1989) and cognitive development in children (Anderson, 2002). A study published in the British Medical Journal also used this task to determine that even moderate drinking of alcohol results in adverse brain outcomes (Topiwala, 2017). The academic journal search tool Google Scholar notes 16,800 articles that refer to the Complex Figure test.

Digit Span

Savonix’s Digit Span task is similar to the Digit Span subtest of the Wechsler Adult Intelligence Scale (Wechsler, 1994). The Forward Digit Span task consists of a number of trials where a series of digits are presented at a constant rate on the device screen. Immediately after each trial, the user is required to enter the digits on a keypad in the order in which they were flashed. In the Reverse Digit Span task, the user is required to enter the digits in reverse order. Sequence length varies between three and 10, with two trials for each length and with trials presented in ascending sequence order. The task ends when the participant fails two trials of any sequence length or when all trials are completed. The outcome variables are the longest sequence lengths correctly completed forwards and backwards. This task is used as a measure of attention and working memory. It is often used in the process of assessing a patient for attention deficit disorders. Rudeland Decka (1974) determined that different hemispheres of the brain are involved with forward vs. backward digit span. Those with left hemisphere dysfunction had a noted disadvantage in the forward digit span task. Meanwhile, subjects with right hemisphere dysfunction performed worse on backward digit span compared to the control group. Digit span scores of seven or less are associated with high specificity in healthy and brain-injured cohorts (Etherton 2005). Digit span was used in a study funded by the Grammy Foundation to assess whether music education improves cognitive function (Zuk 2014). This task was also used as a measurement by Low et al. to determine whether iron supplements improved cognition in children with anemia (Low 2013).

References

1. Nordlund, A., Rolstad, S., Klang, O., Edman, Å., Hansen, S., & Wallin, A. (2010). Two-year outcome of MCI subtypes and aetiologies in the Göteborg MCI study. Journal of Neurology, Neurosurgery & Psychiatry, 81(5), 541-546.

2. Hessen, E., Reinvang, I., Eliassen, C. F., Nordlund, A., Gjerstad, L., Fladby, T., & Wallin, A. (2014). The combination of dysexecutive and amnestic deficits strongly predicts conversion to dementia in young mild cognitive impairment patients: A report from the Gothenburg-Oslo MCI Study. Dementia and geriatric cognitive disorders extra, 4(1), 76-85.