Weight Discrimination Alyssa Figueroa Marissa Jacob
Hypotheses ď‚š The dominant hand group will have less number of errors in their final mean score compared to the nondominant hand group ď‚š The non-dominant hand group will show a greater improvement between their initial mean error score and their final mean error score compared to the dominant hand group ď‚š There will be no significant difference between the final mean times for dominant hand group and nondominant hand group
What does the literature say? Field-dependence-independence as “sensitivity” of the nervous system: supportive evidence with color and weight discrimination
Hypothesized that field-independent participants would perform significantly better than the field-dependent participants on a weight discrimination task 56 participants (soldiers) - Either in field-independent or field-dependent group based on nervous system level of sensitivity 10 black discs varied in weight from 50-86 g Participants were asked to arrange disks in order from lightest to heaviest - 2 trials with dominant hand and 2 trials with non-dominant hand
Hypothesis was supported *Both groups performed better with their dominant hand compared to their non-dominant hand (Fine, 1973)
What does the literature say? Aberrant judgmental pattern of schizophrenic patients in weight discrimination
32 participants (right handed) - 16 chronic schizophrenics (11 female and 5 male) - 16 normal controls (9 female and 7 male)
Weight discrimination task
Categorical conditions - Heavier/lighter - Heavier/lighter/equal
- Heavier/lighter/doubtful Hand conditions - Left, right, and bimanual
Standard weight placed in palm 2 s; comparison weight immediately placed in palm 2 s - Cylindrical plastic weights ranging from 29-71 g for comparison weight and standard weight was 50 g -Screen board prevented participants from seeing their palms and weights
Schizophrenics made more reversal errors than normal group in heavier/lighter condition - Indicated sensory deficits of proprioceptive acuity in schizophrenics
No significant difference in the heavier/lighter/doubtful condition
Increased occurrence of equal judgments in schizophrenic group -Might indicate deficit at the judgmental level and partly from a deficit at the sensory level
(Tanno, Shiihara, & Machiyama, 1999)
What does the literature say? Jiggling a lifted weight does aid discrimination Fact: - Ability to discriminate between weights is affected by the manner of obtaining the stimuli
- Active lifting results in better discrimination than passive pressure - Discrimination improves with the frequency of the lift and the stimulus intensity and number of limb joints involved in the lift Therefore, hypothesized that jiggling objects when estimating their weight should aid discrimination 30 undergraduate students (17 male and 13 female) Cylinders weighing from 50-64 g Blind folded Participants were asks to state whether the weight was heavier or lighter than the standard 50 g weight Hypothesis was correct; there was a significant difference
(Brodie & Ross, 1985)
Subjects Where did we get them:
- Friends and family Characteristics: - Must be female - Must be 18-80 years of age How many?
- 10 subjects in the Dominant Hand Group - 10 subjects in the Non-Dominant Hand Group - Total of 20 participants
How did you get them? - We asked each participant if they would like to volunteer in our activity and once they gave consent we continued on to completing the task.
Research Personnel ď‚š How many? - Two (2) ď‚š Characteristics?
- Female - College students ď‚š What do they have to do? - Explain purpose and procedures of the test to the participant. - Shuffle the labeled containers before each trial - Record the time and number of errors for each trial
Before the Experiment Research Personnel must: o
Location of Test: - Brought study to the participant’s household since equipment is easily transportable
o Equipment - 20 identical containers (colored outside) - 110 pennies - Stop watch - Paper and pen - Marker (number containers on bottom)
Subjects Requirements: - Must meet participant requirements as previously mentioned before - Must give consent to participate in activity/test
During the Experiment ď‚š Subjects will be asked to: - Without turning object over, arrange 10 containers in order according to weight while being timed o Dominant hand group - Only the participants dominant hand will be used for all trials o Non-Dominant hand group - Dominant hand will be used for trials 1, 2, 5, and 6 - Non-Dominant hand will be used for trials 3 and 4
During the Experiment Cont. ď‚š Why do it this way? - To see overall improvement between participants with their non-dominant and dominant hand - To identify a difference between dominant and non-dominant hand final mean error score - To identify a faster final response time in dominant hand group versus non-dominant hand group
During the Experiment Cont. ď‚š When? - Whenever it was convenient for the participant
ď‚š How many trials and why? - The participants will complete a total of 6 trials - In order to get an average value for the initial, practice, and final to get more accurate data
Consent Form ď‚š Permission to Participate in Study - I agree to volunteer in Alyssa Figueroa and Marissa Jacobâ€™s research study. - I know I can quit at any time. - I will not hold TWU responsible if I am injured in the study.
Hypothesis: The dominant hand group will have less number of errors in their final mean score compared to the non-dominant hand group. Dominant Hand vs Non-Dominant Hand Group In Final Mean Error Score t-Test: Two-Sample Assuming Equal Variances Non-dominant Dominant Mean 2.40 1.05 Standard Deviation 0.57 0.76 Variance 0.32 0.58 Observations 10.00 10.00 Pooled Variance 0.45 Hypothesized Mean Difference df t Stat P(T<=t) one-tail t Critical one-tail P(T<=t) two-tail t Critical two-tail
0.00 18.00 4.49 0.00 1.73 0.00 2.10
t(18)=4.49, p<.05 Accept Hypothesis, because the dominant hand group had the least amount of errors in their final mean score
Dominant Hand vs Non-Dominant Hand Group In Final Mean Error Score (Mean + SD)
# of errors
2.50 2.00 1.50
Hypothesis: The non-dominant hand group will show a greater improvement between their initial mean error score and their final mean error score compared to the dominant hand group. Dominant Hand vs Non-Dominant Hand Group In Error Improvement Between Intial and Final Trials t-Test: Two-Sample Assuming Equal Variances Non-dominant Dominant Mean -0.30 0.30 Standard Deviation 0.59 0.59 Variance 0.34 0.34 Observations 10.00 10.00 Pooled Variance 0.34 Hypothesized Mean Difference 0.00 df 18.00 t Stat -2.29 P(T<=t) one-tail 0.02 t Critical one-tail 1.73 P(T<=t) two-tail 0.03 t Critical two-tail 2.10
t(18)=2.29, p<.05 Reject Hypothesis, because the dominant hand group showed the greatest improvement. The non-dominant hand group actually performed worse in their final trial than their initial trial.
Dominant Hand vs Non-Dominant Hand Group In Improvement Between Initial and Final Trials (Mean + SD) 1.00 0.80 0.60
# of errors
0.40 0.20 0.00 -0.20
-0.40 -0.60 -0.80 -1.00
Hypothesis: There will be no significant difference between the final mean times for dominant hand group and non-dominant hand group. Dominant Hand vs Non-Dominant Hand Group In Final Mean Time t-Test: Two-Sample Assuming Equal Variances Non-dominant Dominant Mean Standard Deviation Variance Observations Pooled Variance Hypothesized Mean Difference df t Stat P(T<=t) one-tail t Critical one-tail P(T<=t) two-tail t Critical two-tail
50.25 23.51 552.74 10.00 311.00 0.00 18.00 1.76 0.05 1.73 0.10 2.10
36.40 8.32 69.27 10.00
t(18)=1.76, p>.05 Accept Hypothesis, because p value was greater than .05 and the computed t value was less than the critical t value. Therefore there is no significant difference in final mean times.
Dominant Hand vs. Non-Dominant Hand Group In Final Mean Time (Mean + SD) 80.00
40.00 30.00 20.00 10.00 0.00 Non-dominant
Our Findings ď‚š We believe the dominant hand group improved more in our research study because, the participants are use to constantly using that particular hand on a daily basis. Which, allowed their time to improve and number of errors to decrease as they progressed over several trials of practice. ď‚š We believe the second group didnâ€™t improve as much as the first group because research personnel involved trials that used both dominant and non-dominant hands. Which, potentially lead to their overall time and number of scores to be slightly effected.
Research Design Evaluation ď‚š Yes, we strongly believe that the weight discrimination test design was best used to accurately test our research hypotheses and identify the variables used throughout the study.
Problems ď‚š Did not distinguish 6 and 9 labels on the bottom of containers sufficiently - Added a line under the 9 so participants and research personnel could better understand the difference.
Questions or Comments?
References Brodie, E. E. & Ross, H. E. (1985). Jiggling a lifted weight does aid discrimination. The American Journal of Psychology 98(3), 469-471. Fine, B. J. (1973). Field-dependence-independence as â€œsensitivityâ€? of the nervous system: supportive evidence with color and weight discrimination. Perceptual and Motor Skills 37, 287-295.
Tanno, Y., Shiihara, Y., & Machiyama, Y. (1999). Aberrant judgmental pattern of schizophrenic patients in weight discrimination. Psychiatry and Clinical Neurosciences 53, 477-483.