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Inthis work, through investigating a series of liquid, glassy,and crystalline samples with ultrafast multiple-mode 2D IR and IRtransient absorption methods, we demonstrated that the signal anisotropyof vibrational relaxation-induced heat effects is determined by bothrelative molecular orientations and molecular rotations. If the relativemolecular orientations are randomized or molecular rotations are fastcompared to heat transfer, the signal anisotropy of heat effects iszero. If the relative molecular orientations are anisotropic and themolecular rotations are slow, the signal anisotropy of heat effectscan be nonzero, which is determined by the relative orientations ofthe energy source mode and the heat sensor mode within the same moleculeand in different molecules. We also demonstrated that the correlationbetween the anisotropy value of heat signal and the relative molecularorientations can be quantitatively calculated. [ABSTRACT FROM AUTHOR]