PSGY1014 Lecture 9: Methodological Issues In Psychology PDF

PSGY1014 Lecture 9: Methodological Issues in Psychology By the end of this section, you should know: Limitations of correlational methods The differences between extraneous and confounding variables Considerations in experimental designs How to avoid undesired effects in your results ...

PSGY1014 Lecture 9: Methodological Issues in Psychology By the end of this section, you should know: Limitations of correlational methods The differences between extraneous and confounding variables Considerations in experimental designs How to avoid undesired effects in your results  Correlational methods (refresh your memory!) How two things behave naturally No intervention No Causation  Correlational methods No manipulation Where you sit in Grade in No control the class statistics No randomization Existence of extraneous and confound variables Interest in the class  Experimental methods Manipulation of the IV Independent Grams of drug variable Measure the effect on the DV Causal relationship ̶ Control potential alternative causes ??? Performance in Dependent memory variable  Scientific control Minimize the effect of other variables Extraneous variables ̶ Anything that might potentially impact your results ̶ E.g., light of the room Confounding variables ̶ If there is a direct relationship between the extraneous variable and your DV ̶ E.g., length of the words  Experimental methods Does the drug “memento” improve memory? One group: Memory task Day 1 Day 2 Day 3 Day 4 No drug 100 gr 200 gr 300 gr Within-subjects design  Experimental methods Grams of drug Carry-over effects Performance in memory Experimental methods Are these effects consequence of learning? Solutions: ̶ Counterbalancing conditions (ideally same number per combination)  Experimental methods Subject Day 1 Day 2 Day 3 Day 4 Are these effects consequence 1 No drug 100 gr 200 gr 300 gr 2 100 gr 200 gr 300 gr No drug 3 200 gr 300 gr No drug 100 gr of learning? 4 300 gr No drug 100 gr 200 gr 5 100 gr No drug 200 gr 300 gr 6 No drug 200 gr 300 gr 100 gr Solutions: 7 8 200 gr 300 gr 300 gr 100 gr 100 gr No drug No drug 200 gr ̶ Counterbalancing 9 200 gr 100 gr 300 gr No drug conditions (ideally same 10 100 gr 300 gr No drug 200 gr number per combination) 11 300 gr No drug 200 gr 100 gr 12 No drug 200 gr 100 gr 300 gr 13 300 gr 200 gr 100 gr No drug 14 200 gr 100 gr No drug 300 gr 15 100 gr No drug 300 gr 200 gr 16 No drug 300 gr 200 gr 100 gr Experimental methods Are these effects consequence of learning? Solutions: ̶ Counterbalancing conditions (ideally same number per combination) Experimental methods Are these effects consequence of learning? Solutions: ̶ Counterbalancing conditions (ideally same number per combination) ̶ Control group (with placebo)  Experimental methods Does the drug “memento” improve memory? Four groups: Memory task No drug 100 gr 200 gr 300 gr Between-subjects design Experimental methods  Experimental methods Grams of drug Differences Timing between effects? samples? Performance in memory  Experimental methods Can the effects be explained 6 PM 6 AM 10 AM 11 AM by timing effects? No drug 100 gr 200 gr 300 gr (placebo)  Experimental methods Can the effects be explained 6 PM 6 AM 10 AM 11 AM by timing effects? Solutions: ̶ Approximately same time ̶ Randomize the time for each group No drug 100 gr 200 gr 300 gr (placebo)  Experimental methods Can the effects be explained by differences in groups? ̶ Age? ̶ Intelligence? ̶ … No drug 100 gr 200 gr 300 gr (placebo)  Experimental methods Can the effects be explained by differences in groups? ̶ Age? ̶ Intelligence? ̶ … Solutions: No drug 100 gr 200 gr 300 gr (placebo) ̶ Same age ̶ Randomize participants to each group  Experimental methods Grams of drug Length of Experimenter the words effects Performance in memory Frequency of the words  Other problems Length of the words: Shorts words are better remembered than long words (e.g., Baddeley, Thomson, & Buchanan, 1975) ̶ Block the number of syllables (e.g., only use words with two syllables) ̶ Counterbalance words of different syllables across conditions  Other problems Frequency of the words: Frequent words are better remembered than infrequent words (Gregg, 1976) ̶ Block the frequency of words (e.g., use medium frequency words) ̶ Counterbalance frequency across conditions  Other problems Experimenter effects: Cues from an experimenter that affect the performance of subjects in the experiment ̶ Keep instructions the same (e.g., write the instructions down) ̶ Double-blinded study  Summary Experimental methods allow establishing causal relations when potential confounds are avoided or controlled Both within- and between-subjects designs present advantages and disadvantages. The use of one or another will largely depend on the aims of your study Be aware that you, as experimenter, might affect the performance of your participants