The Timing Perception Measure

by Mark Tommerdahl

Timing perception is derived from your duration discrimination task. This is the test that asks “Which stimulus lasted longer?” The first trial of the task (during training) delivers a 650 msec duration stimulus to one finger and subsequently a 500 msec duration stimulus to the other (a 150 msec difference). Each time the person taking the test identifies the finger that received the longer stimulus correctly, the difference between the two durations on the next trial is reduced. Most people track down to a difference limen of 35-60 msec, and this results in a 100% score for timing perception. If the raw score for DD (on the bottom right hand list of scores on the analysis page) is above that, then the timing perception score will be less than 100%.

The ability to perceive the difference in two stimuli is a network function that relies heavily on the cerebellum. The cerebellum plays a role in accurate timing of events and coordinating many functions including walking, balance and posture. It accomplishes this contribution by organizing inputs from many parts of the brain (including sensory systems) and integrating them to fine tune motor control. Intuitively, it makes sense that the region of the brain that performs these types of time dependent tasks would also play an important role in timing perception.

There were several different research groups that studied timing perception and the role that the cerebellum played in that function. Each of the groups, even though they used different sensory modalities (each group used either tactile, auditory or visual stimuli) blocked activity in the cerebellum and demonstrated that timing perception capacity was greatly diminished. This is also consistent with timing perception results that were obtained from populations with neurological disorders or insults that involve damage or degeneration to the cerebellum. And it is also consistent with our own observations in concussion that when an individual receives a blow to the back of the head (where the cerebellum is located), timing perception is usually diminished.

A note of interest on this topic is that in sports concussion studies, balance is probably one of the most over-rated measures routinely collected. There have been no studies that demonstrated that balance was a problem in the majority of concussed individuals in any reported study. In our own study (200 concussed individuals who were balance tested as well as tested with the Brain Gauge), individuals tested, on average, 13% better 2 days after becoming concussed than they were at baseline (i.e., better than normal!). This compares to 99% of the individuals testing worse than normative values post-concussion with the Brain Gauge. Loss of balance is one of the symptoms that can occur with concussion, but there are many symptoms that result from concussion. Measuring the degree of one possible symptom is a bit like measuring the force from a sneeze to determine if someone has a cold: it might be related, but it probably is not. Measuring the underlying cause of a symptom is much more effective. If timing perception is off, then there is very high probability that timing circuitry involved in the cerebellum (which plays a role in balance) could be damaged. Sometimes the insult to this timing circuitry will result in the loss of balance, and sometimes it won’t. In our current TBI work (which includes more than 300 concussions), it appears that timing perception is usually disrupted in certain conditions, such as when the back of the head is impacted significantly (but this is still a topic of research) or when the blow to the head is significant enough to cause deficits in all of the Brain Gauge scores. If the frontal and pre-frontal cortices are impacted significantly, then your ability to make decisions – regardless of what the decisions are about – will make it difficult to perform any of the tests.

There are a number of papers in the literature that document different neurological disorders that have a degenerative or negative impact on timing perception. If your timing perception is poor, it does not mean that you have one of these conditions! Also note that there are different degrees of poor timing perception. Someone that is mildly sleep deprived will do moderately poorly, someone with migraines will do worse, and individuals with Parkinson’s typically do very poorly.

  • Alzheimer’s
  • ADHD
  • Parkinson’s
  • Lesions to the cerebellum
  • Acute TMS to the cerebellum (TMS used to turn off cerebellum)
  • Schizophrenia
  • Migraine
  • THC
  • Sleep deprivation
  • Huntington’s disease
  • Haloperidol

We will add to this list as we continue with our research and continue to survey the literature of other researchers using this technique.