Unconscious memory

1. Unconscious memory Zoltán Dienes Conscious and unconscious mental processes

2. Unconscious memory You use memory but you are not aware of using memory Types of conscious memory Recollection: Remember target event and details of you yourself in spatiotemporal context. (And you are aware of remembering.) Familiarity: You know you have come across the target item before but you can’t remember context. You are aware of knowing the target item is old.

3. Implicit and explicit tests Warrington and Weiskrantz (1970) gave amnesics and normals a list of words to study (including e.g. “patio”). On a recognition test, amnesics performed worse than normals On stem completion: e.g. Pat - - Subjects were better at words they had seen before, and this priming was not significantly different between amnesics and controls

4. Schacter (1987) Explicit memory tests Make specific reference to, and require recollection of, a specific learning episode. Implicit memory tests Do not refer to prior episodes but are facilitated by them

5. Does performance on implicit tests reflect unconscious memory? Problem: You COULD solve stem completion by use of conscious memory Larry Jacoby Conscious and conscious memory in opposition Jacoby: use opposition logic. Exclusion test: Complete the stem with the first word that comes to mind BUT NOT one from the list Conscious and unconscious memory work in opposition; any tendency for above-baseline priming is plausibly due to unconscious memory

6. Inclusion task: conscious and unconscious memory act in concert Results from exclusion and inclusion combined allows an estimate of the amount of the conscious memory process and the amount of the unconscious memory process (Process Dissociation Procedure: PDP)

7. Memory processes producing experiences that don’t seem like memory Unconscious memory and the illusion of loudness. Jacoby et al 1988 (JEP:LMC) Previously heard and new sentences presented in a background of white noise of varying loudness. => Background noise judged as less loud for old rather than new sentences Subjects told about the effect and told to avoid it are unable to do so: Subjects experience the effect as a perceptual one.

8. Unconscious memory and the illusion of truth Begg, Anas, & Farinacci (1992), Experiment 4 (JEP:G): 1. Learning phase: Subjects presented with obscure statements (like “house mice can run an average of four miles an hour”) labelled as true or false. Half the subjects performed a simultaneous mental arithmetic task (divided attention condition). 2. Test phase: presented with new and old sentences, rate extent to which each is felt to be true. Sleeper effect: Unconscious memory can make a statement seem true.

9. Recollection of source would enable a subject to rate a statement as false if it was labelled false (note conscious and unconscious memory are put in opposition: Exclusion); and to label it as true if labelled true (conscious and unconscious memory act together: Inclusion). experiment 1: old new label: true false .66 .59 .45 (inclusion exclusion baseline)

10. Recollection of source would enable a subject to rate a statement as false if it was labelled false (note conscious and unconscious memory are put in opposition: Exclusion); and to label it as true if labelled true (conscious and unconscious memory act together: Inclusion). experiment 1: old new label: true false .66 .59 .45 (inclusion exclusion baseline) Inclusion > exclusion: There must be some conscious recollection

11. Recollection of source would enable a subject to rate a statement as false if it was labelled false (note conscious and unconscious memory are put in opposition: Exclusion); and to label it as true if labelled true (conscious and unconscious memory act together: Inclusion). experiment 1: old new label: true false .66 .59 .45 (inclusion exclusion baseline) Inclusion > exclusion: There must be some conscious recollection Exclusion > baseline: There must be some ‘unconscious memory’ The secondary task affected conscious memory but not unconscious memory

12. Mere Exposure effect (Zajonc, 1968) - Simple exposure to meaningless shapes enhances subjects attitude towards the shapes - Strength of the effect is often not correlated with recognition accuracy Some evidence for a negative relationship with explicit recognition: - Longer the delay between exposure and testing, larger the effect - Subliminal rather than supraliminal exposure produces stronger effects -> Our conscious experiences are partly reconstructions based on unconscious processes

13. Mandler et al 1987 (JEP:LMC 13 646-648) 1)Irregular shapes flashed for 1 or 2 ms 2)Subjects shown pairs of shapes, one new, one old

14. Information processing under general anaesthesia 1)Do therapeutic suggestions improve recovery? Evans & Richardson 1988 (The Lancet Aug 27 1988, p. 491) 40 hysterectomy patients randomly assigned to: 1)Control group. Heard silence. 2) Experimental group. “You will not feel sick, you will not have any pain . . “ “The operation seems to be going very well and the patient is fine . . . No patient could recall anything.

15.   Control Experimental Post-operative stay(days) 8.4 7.1 sig Periods of High temperature 3.9 2.2 sig Nurses assessment Of recovery Better than expected - 14 1 + 6 16 sig nausea (0-100) 43 28 ns pain distress (0-100) 20.8 18.2 ns

16. 2) standard implicit memory tests Roorda-Hrdlickova et al (1990) Control group (43 patients) Listened to tape of “seaside sounds” after first incision. Experimental group (38 patients): Seaside sounds plus the words Yellow banana green pear Repeatedly for 15 minutes

17. No patient could recall anything that happened during anaesthesia. Asked to name first three vegetables, colours, and fruit that came to mind. Mean number of hits Experimental group 2.35 Control group 0.79 p < .001