Perception of Danger Signals: The Role of Control

Jochen Brandtstadter, Andreas Voss, and Klaus Rothermund

Definition of danger signal: A signal indicating that the line is not clear and

instructing the driver to stop.

Literature review

• Research shows that perceptual process is influenced by dispositions and motivational states which is based on the principle of top- down influences.

• Positivity hypothesis :perceptual and cognitive processes move toward positive stimuli

• Relevance hypothesis: attention is preferentially attracted by stimuli that are relevant for guiding action.

Introduction

• In this study its expected that there will be an increase vigilance or sensitivity when people hold a belief that they can avoid or neutralise averse consequence by appropriate actions.

• Assimilative mode: the person tries to actively correct or prevent the problematic situation.

• Accommodative mode:the tries to adjust to the situation.

AIM OF STUDY

Predicted perceptual effects of control are tested drawing on the paradigm of « illusory conjunctions ».

Method

• A visual search task in which three different letters and colors were briefly shown on a computer screen.

• Participants had to decide whether a specific color combination (probe stimulus) was present in the stimulus set. Points were credited for correct responses.

• The experiment involved a control group and the comparison group (no control).

Participants

• 108 students (85 females and 23 male)Stimulus Material And Design

each stimulus set consisted of 3 letters E,O, and V which were printed in red,yellow or blue.They were presented in a computer screen in a triangular manner.

Procedure

• There was a sequence of practice trial first (324 trials) .

• In the main part, 36 different stimulus sets was presented nine times using different letter color combination.

General trials

• First a fixation point appeared on the screen and around it was the stimulus set (100ms).

• Then a particular letter was shown as a probe stimulus which participants were asked if it was in the stimulus set.

• ADDITIONAL TASK : participants could avoid the loss by correctly indicating the position where the DS appeared (control group) while responses were chosen in a lotery-like manner (no control group).

Analysis

• Nine letter conjuntions were classified in 4 groups:Danger stimulus(DS)other letters in the same color as the DSstimuli sharing form but not color with the DSneutral stimuli sharing neither form nor color with the DS.

For response distributions the parameters of sensitivity (d) and response bias (C) were calculated for each participants.

Results

• Sensitivity: in controllable condition, sensitivity was increased for all types of stimuli involving danger features while for no control group sensitivity was lower for danger stimulus only. Also for control condition, the rate of success was positively correlated with sensitivity for DS indicating that focusing attention on DS inceases defense performance.

CONT

• Response bias: in the control group the tendency to give a false response was reduced for the danger probe while for the no control group it was reduced for the probe stimuli sharing the letter with the danger signal only.

Discussion

Findings in this study converge with the Action- theoritical considerations, people have control over negative consequences when the perceptual system is sensitized or react more vigilantly to the danger signal.Also increase sensitivity for danger stimulus in the control group was accompanied by a reduced response bias.

CONT

• Also high sensitivity for stimuli shown in thesame color as the danger stimulus indicates that color might play a crucial role in that process.

• Lastly the dual process model specifies moderating conditions under which either increase viligence or perceptual inhibition for danger signals should occur.