EN RELACIÓN CON LA REFLEXIÓN SOBRE LA LENGUA (SISTEMA, NORMA Y USO) Y LOS TEXTOS

Cardiovascular measurements

Blood pressure and heart rate were initially monitored by a Rossmax Medical RM-4000 (Rossmax International, Germany) monitor attached to the left wrist, which provided a digital readout of the time, blood pressure and heart rate. The cuff automatically inflated on pressing a button and produced a reading in 60 seconds. Unfortunately this unit failed and was unable to be replaced so subjects 23-43 had their blood pressure taken by a Nissei ES-12G

sphygmomanometer with the cuff placed on the left upper arm. Pulse rate was taken at the wrist and timed using a stopwatch.

Aural Temperature readings

Temperature readings were taken using an IRT 3020 Thermoscan aural thermometer (Kronberg, Germany). The thermoscan produced a reading in one second and was accurate to 0.1 degree Celsius.

Aural temperature was used as it was a non-invasive measure which was able to be carried out quickly. Other methods (such as the use of temperature sensitive tape, as is used on the foreheads of children, to provide continuous readings), were considered but rejected as not accurate enough.

During initial testing of the equipment, the signal from the phone had

interfered with the thermos can. The thermoscan beeped and didn't provide a

reading if placed in the ear alongside the phone. This was why, initially the aim

to test the temperature on the phone side as well as the non-phone side was abandoned. However, with subsequent trials it was found that if the phone was

angled back slightly for the 1-2 seconds it took to take the reading, a reading

could be obtained. A check against a non-electronic thermometer confirmed the readings were accurate. If the probe picked up interference from the phone the thermoscan would beep and not provide a reading. This meant there was a check to ensure the thermoscan was in the correct position relative to the

phone and was reading correctly. If the thermoscan beeped during the experiment the reading was redone. That is why temperature recordings for the right ear start from subject 21. The thermoscan never beeped when readings were taken from the left ear.

Salivary Melatonin levels

A single saliva sample was collected from each subject at the end of each of the

5 sessions, a total of 5 samples per subject. Samples were collected in 5 ml

plastic tubes and immediately frozen. They were later assayed for melatonin concentration using the RIA procedure described in experiment one. A full discussion of the reasons for choosing the method of collection and assay for the determination of melatonin levels has been given in experiment one. The cut off value for the 'low excretor' group was set at 8 pg/ ml or below. This was the same protocol as was used for experiments one and two, adjusted for a slightly earlier start time. Classification was made on the basis of the first control session.

Cognitive Tasks

The following cognitive tasks were used as they are common tests used in psychological assessment and have been extensively validated. Tasks were chosen to assess effects on simple attention, working memory for words and working memory using digits. Two memory task were chosen as manipulation of words in the brain uses a different area to that required for the manipulation of digits.

Digit span working memory task

This was a test for working memory involving numbers. The test is one

commonly used to test for damage to the parietal cortex, which lies adjacent to a phone held against the ear.

Following the protocol reported by Preece (1998) subjects were read a series of

5 two-digit numbers to hold in working memory. After a one minute break, they were presented with a probe number and asked to indicate if that number was in the original list. There were 30 probe numbers, presented

individually. Responses were recorded on to a form by the experimenter. The

score was the number correctly identified as being in the original list. Delayed word recall

This test was chosen as it is commonly used in psychology and forms part of several common neuropsychology test batteries. The task was used by Preece

et al. (1998) in assessing possible effects from a 50 HZ EMF and in a 1999 study

assessing possible effect from a RF E:NIF.

At the start of each session a set of fifteen words was read to the subject to hold in working memory. Words were given at two second intervals. At the end of the session the subject was given one minute to recall as n1any of the words as possible. To avoid practice effects a different set of words was used for each session (sets A to E). To ensure the same set of words was not used for a

particular session across all subjects, the selection of which order the sets were presented in for each subject was randomised. Responses were recorded by the experimenter with the score being the number of words correctly recalled.

Attention Task

The attention task was one that is commonly used in psychology and several forms are available. This was the same task used in experiments one and two. It was considered necessary to include a task that didn't contain a memory

component and was as close as possible to a pure attention task. It is a timed task and "is a measure of several inter-related functions which include

sustained attention, visual scanning, response inhibition and rate of information processing" (Cordon et al., 1997. p.325). Variants of the task have been used by other researchers studying the effects of EMFs (e.g. Beale et al, 1997; Crasson et al., 1999).

This was a paper and pencil test in which a page of numbers is supplied and the

subject was told to put a vertical line through each six on the page. Numbers

were arranged on the page in groups of 5. Subjects were allowed to choose

whether they scanned down the columns or across the rows, but were required

to use the same method each time. The time allowed was 60 seconds. There were 5 pages of numbers, a different one for each session. Each page contained the same numbers but differed in that numbers had been transposed within lines and the order of lines of numbers on the page differed. This was done to reduce practice effects. Responses were recorded by the subject. The attention

task was introduced to the protocol from subject 3 onwards.

Score was number of 6s correctly crossed minus number missed or incorrect numbers crossed.

Experimental Protocol